19th-century explorers John L Stephens and Frederick Catherwood altered our view of the Maya civilisation and uncovered great wonders such as this El Castillo (Kukulkan) pyramid, Mexico. Stephens even bought the Mayan city of Copan for $50 with the mis-guided intention of moving it along the river to US museums. The Mayans were one of the greatest civilisations of all time, building incredible structures without the use of metal tools, horses or carts. Even with these constraints, their buildings are as large as, if not larger than, some of the astounding Egyptian wonders.