As a result, King Sweyn III wanted to establish his own seat of power on the remaining fourth of the island.

[3] While it could not be compared to the archbishop's Hammershus, Lilleborg was nevertheless a fine stronghold and appears to have been easier to defend than the much larger Gamleborg.

There is evidence suggesting the fortress burnt down in 1259 when Prince Jaromar of Rügen stormed and destroyed the "king's stronghold" on Bornholm.

[1][6] It was built on the top of a rocky hill, 16 metres (52 ft) high and, at the time, completely surrounded by the Borresø lake.

Positioned away from the coast, as hill forts might be, Lilleborg was characterized as being suitable as a hiding place during sudden attacks, but not efficient for protecting the coastline.