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Secret site

Flat Holm

Bristol Channel, off Cardiff

An island fort where the first radio signal crossed the sea.

Flat Holm is a small island in the Bristol Channel, fortified with big guns in the 1860s against a French invasion and again in the Second World War. In May 1897 Guglielmo Marconi and George Kemp sent the first radio messages across open sea from Lavernock Point to the island.

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When
1860s–1940s
Where
51.3770, -3.1200
Group
Secret bunkers & war sites

Visiting

Boat trips run from Cardiff Bay in summer.

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