Overlooking the lake, and considered one of the finest early Renaissance buildings in the Nordic region, construction commenced on Vadstena Slott, the family project of the early Vasa kings, in 1545. View their gloomy portraits inside, along with a modest historical display. The furnished upper floors are the most interesting, and be sure to visit the chapel, with its incredible 17-second echo! There are guided tours (in English, adult/child 130/90kr) from mid-July to mid-September; call ahead for times.