Kansas — The Spirit of Avalon, $11.8 Million
It may look fairly unassuming from the outside, but Kansas’s most expensive listing is a home unlike any other on this list. Beneath the six-bedroom main residence is a network of underwater tunnels that are designed specifically for scuba diving. Yes, scuba diving. This underground portion of the home is accessible via a series of grottos throughout the property and leads to an outdoor pond with faux fossils and exotic fish. Also connected to the tunnels is a pool with its own waterfall. Named the Spirit of Avalon after the island of Arthurian legend, this Kansas home is a truly unique, castle-like property—one that sits on 15 prime acres in a small town just outside of Kansas City.