Kilitbahir — "the lock of the sea" — is the European-shore companion to Çanakkale's Çimenlik Castle, built by Mehmed II in 1462 to chain the Dardanelles shut against any unauthorised shipping. Its plan is unusual: a triangular curtain wall enclosing a tall round keep, designed to maximise cannon coverage from the narrow promontory.
Cross from Çanakkale on the ferry to Kilitbahir village (around 10 minutes) and the castle is a five-minute walk uphill. The view back across the strait to Çanakkale is the best in the area. Open to visitors; combine with a longer day on the Gallipoli peninsula for context.