Gåseborg is a prehistoric

hillfort A hillfort is a type of earthwork used as a fortified refuge or defended settlement, located to exploit a rise in elevation for defensive advantage. They are typically European and of the Bronze Age or Iron Age. Some were used in the post-Roma ...

in the

Lake Mälaren A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

district in Sweden. The scientists don't know for certain, but most likely it was built to supervise and control the water fairway below the fort, probably sometime during the late iron age (500-1100 AD). Several major fairways passed right here and from this place the local man in power could control the traffic to

Uppsala Uppsala (, or all ending in , ; archaically spelled ''Upsala'') is the county seat of Uppsala County and the fourth-largest city in Sweden, after Stockholm, Gothenburg, and Malmö. It had 177,074 inhabitants in 2019. Located north of the c ...

Sigtuna Sigtuna () is a locality situated in Sigtuna Municipality, Stockholm County, Sweden with 8,444 inhabitants in 2010. It is the namesake of the municipality even though the seat is in Märsta. Sigtuna is for historical reasons often still referr ...

Birka Birka (''Birca'' in medieval sources), on the island of Björkö (lit. "Birch Island") in present-day Sweden, was an important Viking Age trading center which handled goods from Scandinavia as well as many parts of the European continent and ...

and the western districts of Lake Mälaren.

Images

File:Gåsborg 2.jpg, Gåseborg, inner wall to the left and outer wall to the right File:Gaseborg01.jpg, Wall outside Gåseborg File:Gaseborg02.jpg, The central part of Gåseborg {{DEFAULTSORT:Gaseborg Hill forts in Sweden Prehistoric sites in Europe