Alsnö hus

Sjukarby, Sweden, Sweden

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Alsnö hus refers to the ruins of a medieval royal palace located at Hovgården on Adelsö island near Stockholm, Sweden, in the area historically known as Sjukarby.

First documented in 1200 as a significant royal residence, it was rebuilt around 1270 in brick by King Magnus Ladulås (Magnus Barnlock) as a comfortable summer palace rather than a fortress, situated beside Lake Mälaren amid ancient burial mounds from the Vendel Period.

In 1279, the pivotal Ordinance of Alsnö was issued there, establishing the Swedish nobility as a distinct class and laying foundations for the feudal system. 

The structure fell into ruin by the late 14th century, possibly destroyed in an attack evidenced by numerous crossbow bolts found during 1916-1918 excavations, and today forms part of the UNESCO-listed Birka and Hovgården World Heritage Site preserved by the Swedish National Heritage Board.