One of the most iconic LEGO Star Wars lines is the highly coveted Ultimate Collector Series (UCS). These sets feature bigger versions of beloved ships from the Star Wars universe, with an acute attention to detail.

And while that pop culture phenomenon includes massive attention on the films, the characters, the Light Side and the Dark, a few might look to another galaxy far, far away—that, for parents, could be digging into the bottoms of their bare feet as we speak. LEGO Star Wars sets.

Cloud City may not look the part of a legendary LEGO set, but it has become the most valuable LEGO Star Wars retail release ever, sometimes selling for upwards of $10,000 USD in new condition. Its 698-piece build depicts various environments featured in the mining colony’s appearance in The Empire Strikes Back and is packed with play features.