What is "almarestaket"

Almarestäket, or Stäket, is a strait at the inlet of Lake Mälaren in mid-east Sweden. A fortress existed there between about 1370 and 1517, also named Almarestäket.

A place mentioned as Stocksund by Old Norse author Snorre Sturlasson was once believed to be located here, but is now believed to have been located in Norrström, 2 km to the west.

The strait was of importance before Stockholm was founded in the 14th century, as it guarded the waterway to the significant Swedish medieval cities Uppsala and Sigtuna. For instance, an attack on Sigtuna by Baltic Vikings in 1187 led to a battle at Almarestäket, resulting in the death of Archbishop Johannes.