For $647,000, a Seattle homebuyer tried branching out a little. Originally built in 1944, this four-bedroom, two-bathroom garden cottage located on a dead-end street in the Mount Baker neighborhood comes with a surprising modern amenity: a multilevel treehouse made of yellow cedar that could serve as a magical guest room for friends and family. A spiral staircase with branches for handrails leads to the main home’s deck. In addition to the treehouse and a backyard fire pit, the home includes a studio currently set up as a home office, as well as a storage shed.