St George’s Castle, a Unesco heritage site, was built as a trading post by the Portuguese in 1482, and captured by the Dutch in 1637. It was expanded when slaves replaced gold as the major object of commerce, with storerooms converted into dungeons. The informative tour (included in the entry fee) takes you to the grim dungeons, punishment cells, Door of No Return and the turret room where the British imprisoned the Ashanti king, Prempeh I, for four years.
The Portuguese church, converted into slave auctioning rooms by the Protestant Dutch, houses a museum with simple but super-informative displays on the history and culture of Elmina.