Mystery Castle, built by Boyce Luther Gulley in the 1930s for his daughter Mary Lou, is a quirky and eclectic structure located in Phoenix, Arizona. Constructed from a mishmash of materials like stone, adobe, and even automobile parts, the castle features 18 rooms, a chapel, cantina, and dungeon. Despite its unconventional construction, the castle has become a local landmark and tourist attraction, attracting visitors with its unique charm and intriguing history.