The Mushroom Dome is a pentagonal cabin with a geodesic dome for a roof, surrounded by a wooded farm filled with hundreds of nectar-obsessed hummingbirds. True to its name, it looks like an oversize mushroom. For about half the cost of a night at the Four Seasons, a family of three can spend the weekend in the charming but cramped quarters by booking through Airbnb Inc.
Kitty Mrache became the caretaker of the Mushroom Dome after a friend built it on her property in Santa Cruz County, Calif., near Silicon Valley, and lived there for a while. After her friend got married and moved in with her spouse (they wanted something bigger), Mrache fixed the place up for her children. By 2009, her kids were grown up and living in non-mushroom houses, so she listed the oddball cabin on Airbnb, a budding room-rental site that was less than a year old at the time.