Buttress completes Caernarfon Castle access works

The work, for Cadw, the historic environment service of the Welsh Government, has inserted three new floors of facilities in the medieval King’s Gate and allows visitors to access certain of its upper areas for the first time in centuries.

The castle in Gwynedd, north-west Wales, is one of the most important monuments in the UK. It became one of Wales’s first World Heritage Sites in 1986.


The £5 million project focused on making the castle’s monumental principal gatehouse more accessible with an upper-level wall walk. It aimed to massively improve the visitor experience, especially for those with limited ability to negotiate stairways.


The work has introduced a new layer of architecture to the medieval building in the form of bespoke pieces of ‘furniture’ that sit on top and within the triple-towered gatehouse. The architectural interventions have been created to be physically separate from the castle walls, only touching the building lightly at access points. The new elements consist of prefabricated units and hand-crafted carpentry which have been inserted into the existing structure and can be removed with minimal impact.

Alongside this, conservation work included masonry cleaning, removal of vegetation, repointing and window tracery repairs.


Internally, three new floors of accommodation have been created, housing accessible toilets with changing spaces, a café, gift shop, reception area, staff facilities and storage, as well as new interpretation areas.

On the upper level, a viewing deck with seating has been created. Access is provided via a glazed lift, which enables visitors of all abilities to access this part of the castle.


Architect’s view

One of the greatest things about this project is that it’s not a single piece of architectural design; it’s a collection of interventions that create experiences and improves the facilities for all visitors within the King’s Gate, the principal gatehouse of Caernarfon Castle. The castle itself is an incredible structure, a part of history and we are simply adding another layer to its story.  What we have tried to do with the architecture and these interventions is to slot into that story, in a contemporary way, with the castle acting as the main character.

Picking out just one feature to discuss is very difficult among the many facets of the project, so I’m going to focus on one of the main aspects of the brief: accessibility. Accessibility can be such a variety of things, but in this instance, the main design feature that captures this at its best is the lift. It’s unique, bespoke and was a challenge which we wanted to take on. It wasn’t easy, but it was exciting to get the opportunity to improve this aspect of the visitor experience in such a significant way.

As you can imagine, you say the words lift and castle in the same sentence and they don’t tend to go together; therefore the first task of the project was the discussion of where it would go; is it external or internal? And how it would work for the visitor? Positioning was key. There were a lot of stakeholders involved in those discussions, so it was necessary for a thorough assessment to work out the balance between giving the most access, while being the least impactful to the site as possible. There are three towers within the project, offering a variety of positions and locations for the lift.   We took into consideration such things as getting services to the towers, any limitations on where people could access from the lift and architectural features of the existing castle.


We selected the west tower as it was best suited to give the most access to all the floors of the gatehouse as well as it being the best location in terms of visual impact, for when it comes out onto the top deck. Once we decided on the tower it was then about considering the position within the space given the tower’s octagonal shape and the variety of historic features such as fireplaces, windows, doorways, arrow loops and corbels at each level. No two floors are the same, so we decided on what is essentially the clearest wall from the ground up to the second floor: which wouldn’t obstruct any of the existing architectural features of the rooms: and would allow the lift to sit comfortably within the space.

How the lift opened onto the top deck was a key part of our considerations. We carried out a full visual assessment from all the other towers within the castle to see what impact this new structure having come out of a tower would have, as well as the views from the town outside.

When it came to the actual design of the lift, there were no set precedents to lean on – we were starting with a backdrop of a medieval tower and introducing a modern structure that needed to be both reversible and clearly contemporary.

To my mind it always needed to read as a standalone feature that, whilst functional, also needed to be beautiful. It would be a subservient but celebratory intervention. By adopting a simple material palette and design language across the project, each part could have its own identity whilst still being read as a collective piece of architecture. In this case, it was the simple use of steel and glass to create a bespoke panoramic lift. It takes the visitor from the ground floor, through the first-floor café, perforating the external viewing platform and offering completely unobstructed views and panorama of the scenic surrounding areas towards the Menai Strait and the mountains of North Wales.

The overall ethos of the project was to not shy away from celebrating the new architecture as clearly modern interventions that reflected the grandeur of the castle in a contemporary way. We didn’t want to hide the lift, so glass is heavily utilised to allow visitors to still read the stonework through it and experience the space as a medieval octagonal form.


The colour and material palette supports the need for simple, clean, modern lines which contrast with the medieval stone. Naturally, we wanted to get the glass as transparent as possible and selected a low iron glass to reduce the green tint; for consistency this was used on the lift, for the windows, and the balustrading. For all the metal work throughout the project, (including the fixtures and fittings and structure within the lift), we selected a green/grey tone which was chosen to be a strong colour against the masonry; to complement rather than disappear. The lift’s floorplate is finished in a local slate tile and boldly engraved with the World Heritage Site logo. The simple perimeter lighting to the floor and ceiling highlights the lift’s modern structure, echoing our vision that the lift is itself a contemporary insertion that should be celebrated and not concealed.

Collectively with the engineers we pushed to create something a little bit different to achieve visual aesthetics. The lift shaft is only enclosed with glass on three sides with the stone wall of the castle forming the back; we wanted one less barrier to the visitor having the 360° view from inside the lift car. The lift itself is a frameless fully glazed lift car and the doors are under-driven, so the mechanics can sit within the floor plates.

Moving on to the structure of the lift, the steelwork is not fixed to any of the existing stonework, but all supported off new steelwork within the floors, making it completely reversible with no physical contact with the castle. The structural steel frame is made up of a series of ring beams at each floor level and at the head of the doors – reducing the amount of structure on show; it’s essentially a two-column frame that sits in line with all the mechanics of the lift.


To pick up a little bit more on the theme of accessibility, the lift is a major part of that and is a key moment in the narrative of the castle which allows a wider audience access to areas of the castle.  Beyond that, if we are encouraging more people to attend the castle with a diverse set of needs, then we also needed to provide facilities to support that, and we’re pleased that we achieved three accessible WCs and changing place facilities within the interior of the castle.

Just to close out and come full circle is the intellectual access that we’ve also been able to bring to the project. Through the interpretation, which is so integral to the architecture, we’ve introduced a series of sculptures and integrated features such as the glass floors, stained glass window and the downpipes, that tells the story of The Hands That Built the Castle, which is a completely different narrative to what people have seen before. It celebrates everybody from the labourer, the mason, the carpenter, and the chamberlain, to the King himself and I think having it so integrated has helped bring a different story to the castle and improve that intellectual accessibility beyond just the physical features that we’ve installed.

Lucy Ashcroft, senior architect, Buttress


Client’s view

There are many complex design facets to this project.  From the very early days, Buttress did not shy away from what could have been an intimidating project, working on medieval towers within a World Heritage site. To deliver at that sort of scale makes the Kings Gate project remarkable. What also made the project outstanding was that Buttress envisioned and then kept to the concept throughout.  They were incredibly confident and informed, which resulted in their approach being inspiring to the team around them.

One of the significant interventions were the frameless balustrades – they really couldn’t have been anything other than glass.  They were very carefully considered – tall enough to comfortably lean on without obstructing the view – and provide opportunity to pause and survey the castle wards. The bespoke benches and tiered seating, which sit beautifully in harmony with the medieval stonework, both respect The Hands that Built the Castle narrative. All the required, modern, infrastructure was dealt with sensitively and in-line with our philosophy of reversibility and doing no harm. The design and insertion of a fully glazed lift, within a medieval tower is, in our opinion, unrivalled.

The use of technology has been outstanding as models can only take understanding the concept to a point. Buttress used virtual reality to ensure that we could walk around the spaces and get an understanding of the concept and its possibilities. We found that this was of real benefit to the scheme at a very early stage.

To deliver a project of this nature is truly remarkable and a testament to Buttress’s skill.

Chris Wilson, head of conservation, Cadw



Project data

Start on site November 2020 (enabling phase November 2019)
Completion March 2023 (enabling phase October 2020)
Gross internal floor area 539 m2
Gross (internal + external) floor area 1260 m2
Form of contract JCT Standard Building Contract, procurement route through Cadw framework
Construction cost £5 million
Construction cost per m2 approx £4,000
Architect Buttress
Client Cadw
Structural engineer Mann Williams
M&E consultant Silcock Leedham
QS SP Projects
Interpretation consultant Hotrod Creations
Principal designer Buttress
Approved building inspector Gwynedd Council
Main contractor Grosvenor Construction
CAD software used Revit