Diu Fort sits on the eastern tip of the island, built by the Portuguese in the 1530s and expanded over the following decades into one of the most formidable coastal fortifications on the Arabian Sea. Thick double ramparts, a moat cut into the rock, and a scatter of old cannons still facing out to sea give a real sense of how seriously the Portuguese defended this outpost.
A lighthouse stands at the seaward end, and the fort's upper levels give sweeping views back over the old town and the water. Parts of the complex once served as a jail; other sections are gently crumbling and worth exploring carefully. Sunset is the best time to visit, when the light on the old stone and the empty ramparts is at its most atmospheric.