Designed and built in the 1960s by Polish architect Wiktor Lipiński, the man responsible for the famed UFO-like observatory atop Śnieżka in the Karkonosze Mountains, this unique igloo structure served as the architect's private home until his death in 2005. Located in an all-too-normal leafy neighbourhood of boring German villas and stocky single-family houses, Lipiński's creation was rumoured to be the result of an affair with an Innuit woman; alas, the real reason for far less exciting: Lipiński wanted to experiment with building a dome that had the same wall width at every point - something that likely hadn't been attempted before, as similar structures were normally thicker near the ground. An additional purpose was to simply build a cheaper house, and this proved to be a success: compared to houses with the same square footage, Lipiński's igloo cost 30% less. A major hurdle, however, was to secure the manpower required to build the dome - contractors backed out soon after realising what was in store, leading Lipiński to construct most of the house with his own hands. Today, the home is still owned by the architect's relatives and remains closed to the public, but feel free to peek over the low hedge and marvel at some retro-futurism.