The Pueblo Levee Project in Pueblo, Colorado, USA has produced the largest mural in the world, at 16,554.8 m² (178,200 ft²). The mural is almost 3.21 km (2 miles) long and 17.67m (58 ft) tall.
Founded in the 1970s, the mural contains the back-to-back contributions of thousands of artists aged five to 65. The art varies as much as the artists - depicting everything from the History of Women to Andy Warhol replicas. It costs nothing to add your own bit to the mural and currently only recycled paint is allowed to be used.
Comments below may relate to previous holders of this record.