Tucked beneath the bridge that links Gamla Stan and Norrmalm, this child-friendly museum was established when construction workers preparing to build a car park here in the late 1970s unearthed foundations from the 1530s. The ancient walls were preserved as found, and a museum was built around them. The circular plan leads visitors through faithful reconstructions of typical homes, markets and workshops from medieval Stockholm. Tickets are valid for one year.

As with most Stockholm museums, there are plenty of hands-on and multimedia elements here to bring history to life and keep the yawns at bay. Highlights include the 1520s-era ship Riddarsholm, a display about Gallows Hill, and a mysterious gated tunnel that leads through many kilometres of brick wall to the castle.