The ruins of the Maasi fortified castle are located off the Orissaare-Leisi road at the 4 kilometer signpost, 500 meters to the north.
The new location for the Livonian Order's castle was selected to be at the mouth of the Vaike Vain based on the suitability of the harbor, after the destruction of their stronghold at Poide during the uprisings of St. George's Night (1343).
To quote the Livonian Chronicle: "Master Burchard built a well fortified stronghold on Saaremaa, which Brother Goswin later enlarged." in reality, the building of the stronghold lasted longer than the lives of two Brothers mentioned. Construction lasted from the 14th century well into the 16th century. Studies of the remaining walls have indicated that Maasi consisted of a square tower-shaped structure that was surrounded by loosely square-shaped walls.
Apparently the tower main structure (47m x 12m) was built in two stages. The first story consisted of three vaulted rooms. The walls were furnished with semi-circular cannon towers that were open at the top.
The politics of Denmark and Sweden sealed the fate of Maasi. In 1564 the King of Denmark purchased the areas of Saaremaa that included Maasi. Twice, in 1568 and 1574 the Swedes were able to recapture Maasi for short periods. Finally, in 1576 King Frederik of Denmark gave the order to destroy the Maasi fortifications.
Work has recently started on cleaning and conserving the remaining ruins.