If you made a list of Tulsa's quirkiest buildings, odds are the Cave House would be right at the top. Located a few blocks west of downtown, the Cave House has a unique history dating back to the 1920s when it was originally built as the Cave Garden Restaurant. During the day, the restaurant would serve food on picnic tables outside, but after night fell the restaurant became a speakeasy. Patrons would go in a secret tunnel through the fireplace that led all the way back to a big room under the hill. The tunnel to the secret room has since been sealed off with concrete for reasons unknown.

Today, the house is somewhat of a museum dedicated to a piece of Tulsa's history. With advance notice, you can schedule a guided tour of the house to see its meandering halls and extremely steep staircase. Sometimes called the Flintstone House, the outside is marked by a sign offering "I've always wanted to see inside" tours. While on a tour, you'll get to see this one-of-a-kind architectural attraction and hear stories of its colorful history.

The current owner has decorated the interior with a nod to the home's previous occupants. Visitors will see a set of minivan seats in memory of two mechanics, as well as a key tree for the mysterious key woman who is said to have lived in and haunted the house. While in the house, several visitors reported losing their keys, which later turned up near a hill where no one had been walking. Others have reported seeing the ghost of the original owner in the parlor. This unique structure was once featured on HGTV's "Home Strange Home" and in the book "Weird Oklahoma."