The powerful citadel of Niókastro overlooking the town and bay was built by the Turks in the 16C on the site of an earlier structure; but it was much altered in 1829 by the French, who added the great cannon emplacements to the walls and the pentagonal keep. Don't miss the large building to the left of the entrance housing the collection of the French Philhellene (''friend of the Greeks'') René Puaux featuring objects closely associated with the struggle for Greek independence.