The Tour Tanguy is a 14th-century round tower on a rocky promontory beside the Penfeld, directly across the river from the château. It is one of the few medieval structures in Brest and houses a small museum of the city's history before the war — a collection of dioramas and illustrations showing what old Brest looked like before Allied bombs reduced it to rubble.
The museum is modest but the tower itself is atmospheric, and the position — on a rocky knoll beside the Penfeld with the château and the harbour visible from the top — is excellent. It is free to enter and makes a good companion visit to the Château de Brest across the swing bridge. The dioramas of pre-war Brest are poignant for the city they depict: a dense, medieval urban fabric that no longer exists anywhere but in these models.