If you've ever travelled along the M4 into south Wales you've undoubtedly seen it. Looming large in the distance atop of a hill sits a huge yellow-bricked building with a Welsh flag waving proudly for all to see. It never fails to catch the attention or provoke comments like: "I'd love to stay there one day" or: "I wonder what it's like inside".

The Celtic Manor Resort is one of Wales' only five-star hotels and leisure complexes. Set in 2,000 acres of parkland in Usk Valley that unmissable sight as we know it has been around for 25 years. But its history is far richer than that. When Celtic Inns Ltd purchased a derelict Manor House in 1980 few people could have imagined that it would become just a small part of such a prestigious and internationally-recognised destination.

The vision came from the company chairman, Sir Terry Matthews, a successful entrepreneur who was born in the Manor House during its former life as the Lydia Beynon Maternity Hospital. He has strong family ties in the area but his decision to buy his birthplace was not purely sentimental. He was disappointed by the lack of local hotel accommodation for Canadian engineers and managers who were helping set up a new European manufacturing and office base for his Mitel company in nearby Caldicot. For the latest Welsh news delivered to your inbox sign up to our newsletter.

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The Manor House in 1951
The Manor House in 1951
A group of nurses at the Manor House
A group of nurses at the Manor House
A woman holding babies
Lydia Beynon Nursery
Sir Terry Matthews, chairman of the Celtic Manor Resort, pictured in 2008
Sir Terry Matthews, chairman of the Celtic Manor Resort, pictured in 2008

The stately home, originally known as Coldra House and now The Manor House, dates back from the mid-19th century, originally with a modest 17 bedrooms. It was the home of Thomas Powell Junior, the son of a leading figure in the coal and iron trade. To this day you can stay in rooms there, which are rich in character with historic period features and country house décor.

But in 1999 the landscape was about to change entirely. The Manor House had grown from 17 to 70 bedrooms but that expansion was nothing compared to the building of the new £120m five-star resort hotel which boasts 330 bedrooms. It has been a major success and today, on average, it has an 86 to 87% occupancy rate. It is a major employer for the area with 1,500 staff working across the site. Through the years it has hosted innumerable famous faces including former US president Barack Obama, Jay-Z and Beyoncé, Kylie Minogue, Michael Douglas and Catherine Zeta-Jones, Bruce Springsteen, Sir Paul McCartney, Nicole Scherzinger, Luke Evans, Gareth Bale, and Katherine Jenkins.

But the hotel is just one element of the business, it has three championship golf courses, an award-winning luxury spa and treatment room facility, a state-of-the-art convention centre for 1,500 delegates, and five different hotel restaurants and two bars. When walking through the doors of its entrance you cannot help but be taken aback by the sheer size of the place with the huge number of levels ahead of your eyes something akin to a sight you may expect to see in Las Vegas.

The hotel lobby
What you see when you first walk through the entrance of the hotel
One of the many unique sculptures which can be seen in the lobby of the hotel
One of the many unique sculptures which can be seen in the lobby of the hotel
Inside one of the Signature Collection rooms
Inside one of the Signature Collection rooms
The indoor pool
The indoor pool

The resort achieved major worldwide recognition in 2010 when it hosted the Ryder Cup – the biennial men's golf competition between teams from Europe and the United States. It was something of the culmination of a dream for Sir Terry whose chance meeting with legendary golf course architect Robert Trent Jones, whose family hailed from Aberystwyth, turned a vague notion of wanting to add a golf course to his new hotel into a reality and led eventually to ambitions to stage the major sporting event.

It welcomed 45,000 spectators every day and well and truly put the resort on the map as a golfing destination. Unsurprisingly the golfing quarters are filled with reminders of the huge occasion including a tree sculpture of the numbers 2010 and canvas pictures and memorabilia throughout the clubhouse of the players in action. Today, in the height of summer during the months of May to August, it sees around 550 golfers take to its three courses – The Roman Road, The Twenty Ten, and The Montgomerie – on a daily basis. It means everything has to be in tip-top condition for its members and during the summer the estates team is made up of around 65 people with 20 fewer during the winter in times of lesser demand.

The 17th green of the Twenty Ten Course at Celtic Manor Resort
The 17th green of the Twenty Ten Course at Celtic Manor Resort
A floral display showing '2010'
2010 was a famous year for Celtic Manor Resort as it hosted the Ryder Cup
Inside the members' locker room area
Inside the members' locker room area where there are reminders of the the past everywhere you look
Plaques are on some lockers showing the ones that were used by the golfers who took part in the 2010 Ryder Cup including this one which Tiger Woods used
Plaques are on some lockers showing the ones that were used by the golfers who took part in the 2010 Ryder Cup including this one which Tiger Woods used

One of the men responsible for ensuring its quality is Gary Connell who first started working at the resort in March 2000. Moving to Wales from his hometown of Troon in Scotland and following his desire to get back into working around tournament golf – having caught wind that there was word of the Ryder Cup being hosted there – he was brought in by golf course director Jim McKenzie to take on the role of head greenkeeper. He was "awestruck" by the course's size and his 6am-start role saw him lead alterations to greens and bunkers, with variation in the winter, along with day-to-day maintenance and ensuring the presentation was up to scratch. And it's something of a military operation with the process being a lot more complex than you'd think.

Gary Connell sat in a golf buggy
Gary Connell is ecology and environmental stewardship manager at the resort

Mr Connell said: "When you cut grass so often you've also got to feed it. It's a constant being out there with the spray, putting food on, and then because you're putting a lot of food on the greens it gets susceptible to disease, so you have to think about that. If you've got a dry summer you have to think about wetting agents – you have to think about a lot of that sort of stuff. The good thing is if we start in the summer at 6am the golfers aren't normally out there until 7.30am so we've got a bit of time to get in front – then the guys know to work around the golf later on. We try and stay away from the golfers, because we don't want to be seen to be annoying them with the machines, but it's an ongoing thing. You start something on a Monday and finish on a Tuesday, start something on a Tuesday and finish on a Wednesday, and you try and get so much done by the end of the week as you're conscious that it is at its busiest at the weekend."

The 58-year-old now performs the role of ecology and environmental stewardship manager – a role he started in May last year. Efforts are being made to diversify the species you see on the grounds. Bird boxes have been erected and wildflower areas are being created along with wildlife corridors for dormice. The presence of species of dragonfly can be found on site which Mr Connell said shows the Celtic Manor is one of the top places in Wales for water quality as they would not be there otherwise. There are even 'bug hotels' which be spotted around the grounds, which are fully themed with signs reading: 'Celtic Manor bug hotel. Please do not disturb. Vacancies.'

A bug hotel
Even the bugs have accommodation on site
Bird boxes fixed to trees
Bird boxes have been installed as part of efforts to diversify the species you see on the grounds

Brian Duncan is head of golf and retail at the resort having joined in July 2005. He was looking for a role in golf, having initially toyed with the idea of turning professional himself, but fell into the operational side of the business. He explained how he worked his way up through almost every role and got to experience the atmosphere of the Ryder Cup first-hand as part of the golf management team, recalling "the incredible buzz around the resort" at the time. Today his role focuses on delivering top-quality service for golf members and ensuring it matches their expectations.

Brian Duncan stands on a balcony with greenery behind him
Head of golf and retail Brian Duncan
Pictures on a wall
Reminders of the Ryder Cup and other golfing events are proudly displayed everywhere

The 39-year-old said: "It's about working with the team to ensure that five-star delivery consistently and creating memorable experiences. The golf side of things at Celtic Manor is huge to the overall operation – especially in that summer season. That history of having the Ryder Cup here – there was a massive boom straight after and it really raised the profile of the resort having it here. Even now, although it was 14 years ago, still having the tour events year in year out has continued that profile. I have been here 18 years and that in itself says a lot. I came straight out of university and it was one of my first jobs. The team resort-wide is fantastic. It is a family. A lot of the reason why people stay for such a long period of time is because there's so much going on – you're not doing the same thing day in day out and you've got the opportunity to work with different departments and be involved in different projects."

But it is not just the golf which has earned the resort plaudits. It boasts a range of restaurants to suit all taste buds including the two AA rosette award-winning Steak on Six which, as the name suggests, serves up a menu of steak options from Welsh beef sirloin to Scottish beef rump, English rib eye, and Irish beef fillet. There are also other options such as duck breast, wild sea bass, and a Welsh rack of lamb on its main menu.

Another option is Pad, also AA rosette-awarded, which was developed in collaboration with chef, restaurateur, and 2013 MasterChef finalist Larkin Cen with a menu inspired by travels across Asia and featuring everything from curries with creativity and wok pad Thai to bao buns and meat dishes. Rafters, The Grill, and the Olive Tree and Garden Room also offer plenty of options for diners. Try WalesOnline Premium for FREE by clicking here for no ads, fun puzzles and brilliant new features.

Michael Bates is executive chef across all of the resort's restaurants with 60 staff members overall. Each restaurant has a head chef and a sous chef with alternating menus and menu changes two to three times a year. He also oversees a collaboration with the University of Birmingham to help bring through budding chefs for the future with 17 culinary degree students at present.

Executive chef Michael Bates
Executive chef Michael Bates
Inside one of the Celtic Manor Resort's restaurants Steak on Six
Inside one of the Celtic Manor Resort's restaurants Steak on Six

Mr Bates, from Newport, has been on board since even before the resort hotel as we know it was built with his time working there dating back to 1995. The 63-year-old said: "There was a chef called Trevor Jones and he was down in the old Manor. We went to college together. He rang me up and asked me to join the Celtic and I opened up the golf club back in 1995, which is The Grill now. The resort hotel was still being built and every employee would get to have a site visit to familiarise ourselves with the building. I moved into banqueting and then became executive chef. It's very much been part of my whole life really.

"I did leave for five years where we opened our own business, The White Hart Village Inn in Usk, which we made a success of. Our first grandchild was born and we wanted to be closer to home. But I then had a phone call to come back. I always felt like I belonged to the Celtic because of our morals and what the Celtic believes in, I believe in, so I returned. It's a family. Although we're very, very big it's a family. It is a business at the end of the day but it's a great place to work. What we do at each different restaurant is completely different to one another. We have two rosettes at Steak on Six, one at Rafters, one at Pad, so obviously there is a certain level that we attain to."

Some of the shining stars of the hotel are the ones who are seen waiting on and serving customers day in and day out. One of those people is Gary Morgan who has worked as a food and beverage associate at the resort for eight years. It was a change of career for him having been a steelworker for 35 years at Llanwern. He took early redundancy before learning of the new career path at the major hotel in his hometown. He works four days a week in the breakfast area of one of the hotel's restaurants.

Food and beverage associate Gary Morgan
Food and beverage associate Gary Morgan

The 67-year-old, who has nine grandchildren, explained how his job came about. He said: "I think my wife was fed up of me. She went online and found the application for this job, which I knew nothing about, and the rest is history. In the morning I open up – putting out all the buffets, teas, and coffees. I really enjoy being here – there's loads of different people you get to talk to and see different faces, and the guests are brilliant. I always work Christmas Day and it's lovely to see all the happy faces."

Over at Merlins bar is Simona Fabianova, a waitress who has worked at the resort for more than two years. She began as a casual member of staff and enjoyed working there so much that she has since become a permanent member of the team. Her duties involve taking orders and serving drinks and food to customers.

Simona Fabianova is a waitress at the resort
Simona Fabianova is a waitress at the resort

The 21-year-old said: "My cousin's girlfriend works here and she told me that Celtic needed people and after some time working casual I liked being here so I decided to go full-time. I'm from Slovakia and a lot of people here are from different backgrounds, which makes you feel comfortable and everyone has been really nice to me. We are all friends here and we enjoy nights out together outside of work too."

Perhaps one of the busiest men of all at the site is resort operations director David Griffin. He juggles overseeing the divisions of rooms and housekeeping, food and beverage, golf, spa and leisure, activities, conferences, and banqueting. He explained how "no two days are the same" with the business being conferences-led from Monday to Thursday and the leisure market taking over from Friday to Sunday with families visiting in their numbers. There's plenty for families to enjoy with archery, a mini golf course with holes styled on famous golf courses, forest jump high ropes, and laser combat. Mr Griffin said guest feedback is very important and time is put aside every Monday to go through the feedback shared by those who have stayed in order to constantly strive to improve with the focus on giving people a memorable time so that they want to return.

Resort operations director David Griffin
Resort operations director David Griffin

Mr Griffin, who has worked at the resort for four and a half years, said: "We diversify and change our business strategy frequently and the team is very dynamic, focusing on delivering on the requirements for our guests. When it comes to families we have much more of a focus on the activity market and more of a kids' buffet with things like Dylan the Dragon pancakes – he's our mascot and he comes out and meets all the kids. The great thing here is we've got a good, stable team who have been here a long time. It's very family-orientated, everyone works for each other, and when there's a need to go over and above the team are very committed to doing that. It's from the top down and the bottom up.

"We had a guest recently who had a bad foot and it was a case of putting an ice bucket and some towels in their room and the way they responded to that the next morning – those little touches, moments of magic we call them, we have the ability in hospitality to deliver those in bucket loads. To receive those bits of positive feedback gives us a real sense of pride. Everyone who comes to work is proud to be here.

"For me the proudest moments are what the team has achieved – without that I could not do my job. The Celtic has been here for many, many years and without the foresight of Sir Terry we wouldn't see here what we see today and it also comes down to individuals such as Ian Edwards, who has been here for many, many years, being passionate to drive the business in the right direction. There's not any other hospitality business which does all that we do in Wale and I'd even question in the UK when you look at what we've got to offer with the ICCW (International Convention Centre Wales) next door and the leisure family market here. It is important to recognise what a great business this is in Wales on your doorstep and for people to come and enjoy it.

"For the year ahead we're keen to explore and reintroduce the Celtic Manor own events that we used to run with things like celebrity golf and polo. One thing Sir Terry has always been passionate about is ensuring the door is open to the community. We'll also be opening a new hotel, Ty Hotel Newport, on the other side of the roundabout as an addition to the Celtic Collection, which is a very exciting project for us and will be opening in June this year."

The Celtic Manor Resort is one of the jewels in the crown of Wales' hospitality industry and has obtained something of an iconic status for generations by those who have looked on and daydreamed of what a getaway would be like there as they travel at 50mph along that stretch of the motorway. The resort hotel marks its 25th birthday this summer and if you still haven't visited now might just be time for you to finally go along and find out what all the fuss is about. Join our WhatsApp news community here for the latest breaking news.