Almarestäket's castle
Almarestäket's castle (or Sankt Erik's castle) is a medieval castle ruin in Upplands-Bro municipality in Stockholm County. The complex is named after Eric IX of Sweden and was once one of Sweden's strongest and most famous castles, located at the important choke point of Almarestäket, a strait at the inlet to Lake Mälaren. Almarestäket's castle is listed as an ancient monument by the Swedish National Heritage Board.