Beneath the Walls: Cardiff Castle’s Wartime Tunnels

Beneath the Walls: Cardiff Castle’s Wartime Tunnels

Photo. During the Second World War, extensive tunnels within the stone walls of Cardiff Castle were transformed into air-raid shelters. © Travel Explorations. 

Beyond its towers and grand rooms, Cardiff Castle holds a lesser-known story beneath its walls. During the Second World War, the castle’s internal tunnels were transformed into air-raid shelters. Between 1939 and 1945, as bombs fell on Cardiff, these passageways became a refuge for up to 2,000 residents and workers seeking safety from the Blitz.

The tunnels themselves weren’t built for war. They were originally created in the 1880s by the 4th Marquess of Bute as part of a project to expose and showcase the Roman walls. Intended as a private walkway and architectural feature, they later took on a very different role when conflict reached Britain’s shores.

In wartime, the narrow stone corridors were fitted out with bunk beds, toilets, and first-aid posts. Special ramps from Duke Street and Kingsway allowed people to enter quickly during air-raid sirens. What had once been a Victorian curiosity became a lifeline.

Today, walking through these passages feels different from exploring the castle above. The walls are close, the air is cool, and it’s easy to imagine families waiting out the sound of explosions overhead. It’s one of the most striking parts of a visit, not for its grandeur, but for the human stories it holds.

Walking through the tunnels today feels very different from exploring the castle above. Upstairs, there’s colour, decoration, and grandeur. Down here, the atmosphere shifts. The stone walls feel closer. The lighting is softer. The air is cooler. It’s quiet, but not in a peaceful way. It’s the kind of quiet that makes you think.

I found myself slowing down as I moved through the passageways. It’s easy to imagine families gathered on the bunks, children trying to sleep, workers waiting for the all-clear. Standing there, I tried to picture the sound of sirens echoing through the streets outside. The contrast between the castle’s beauty and the fear people must have felt in these tunnels is striking.

Tried to imagine how it was for people searching safety in an extraordinary time. In those dimly lit passages, families huddled together, sharing blankets, songs, and whispered hopes while the world above shook with uncertainty.

The darkness and sounds gave me a strong impression how life here was then. What makes those tunnels inspiring isn’t just their purpose as shelter, but the spirit they protected. They held resilience. They held community. They held the unbroken belief that even in the darkest moments, people can stand together and wait for the light to return.

Walking through them, I could almost feel that determination lingering in the air - a reminder that strength isn’t always loud or heroic. Sometimes it’s simply the act of holding on, side by side, until the storm passes.For me, this part of Cardiff Castle was the most memorable. Not because it’s the most impressive, but because it feels the most human. It tells a story of resilience and adaptation, of a historic landmark stepping in to protect its community.

These tunnels are more than a hidden feature. They are a reminder that even places built for power and prestige can become shelters in times of crisis.

Stein Morten Lund, 24th January 2026

Additional information
During the Second World War, the tunnels carved into the hillside became a refuge for thousands. Read more about the Cardiff Castle tunnels on Cardiff Castle information website.