Björn Järnsidas hög, Viking burial mound in Ekerö Municipality, Sweden

Björn Järnsidas hög is a royal burial mound on Munsön in Lake Mälaren, Ekerö Municipality. It measures 20 metres in diameter and five metres high, and forms part of a grave field of 150 ancient monuments: five burial mounds, a runestone and about 145 round stone settings. The runestone fragment U 13 lies on top of the mound.

The burial field around the mound is dated to the Vendel period, 550–800 AD, and is thought to have belonged to the royal estate at Husby. The runestone fragment U 13 on top of the mound is probably from the late 1000s, several hundred years younger than the grave. According to legend, Björn Järnsida lies buried in the mound.

This burial site is part of a cluster of grave mounds that reveal how Vikings honored their dead through earthen monuments. The grouping shows family connections and the importance they placed on shared burial grounds.

The site is located along Björn Järnsidas väg road heading north and offers free access for visitors. Wear sturdy footwear, as the wooded surroundings can be uneven and occasionally muddy.

The runestone on the summit, U 13, is only a fragment, so its inscription is incomplete. It is probably from the late 1000s, several hundred years younger than the Vendel-period mound beneath it. The stone was thus placed on a grave far older than itself.