Mystery Castle, House and architectural landmark in Phoenix, Arizona, United States

Mystery Castle is an eighteen-room, three-storey house in the foothills of South Mountain Park, built in the 1930s by Boyce Luther Gulley from stone, adobe, automobile parts, salvaged mine rail tracks and telephone poles. Its stepped stone walls, barred windows with striped awnings, a wooden balcony and a metal weather vane are visible from outside. Inside are a chapel, a cantina and a dungeon, and parts of the building remain unfinished.

Boyce Luther Gulley, a Seattle native, was diagnosed with tuberculosis in 1929 and moved to the Arizona desert, where he began building the castle in the 1930s as a gift for his daughter Mary Lou. He died in 1945; Mary Lou and her mother learned they had inherited the property and moved in soon after. A Life magazine article of January 26, 1948 brought the house its name and fame, and tours began that same year.

The castle's name comes from a January 26, 1948 Life magazine article, "Life Visits a Mystery Castle," which showed Mary Lou Gulley on the cantilever staircase to the roof. She and her mother began giving tours that same year. Inside are arches of varied stones, wall drawings of dances and masks, and a cupboard of shoes carved from stone.

The castle stands in the foothills of South Mountain Park, south of downtown Phoenix, and is reached by car. Parts of the 18-room, three-story structure remain unfinished, and electricity and plumbing were only added in 1992. Tours, begun by Mary Lou Gulley and her mother in 1948, have since been suspended; the property is maintained by the Mystery Castle Foundation.

A notable feature is the second-floor wishing well that was once connected to a ground-level bar through a pulley system designed to move drinks between levels. This detail reveals the builder's ingenuity in solving everyday needs with improvised engineering.