1 In 1841, an American explorer called John Lloyd Stephens discovered the Mayan city of Chichen Itza in Mexico. 2 John Lloyd Stephens believed the city dated back to around 600 AD. 3 They grew corn, beans and tomatoes for food. 4 In Chichen Itza, the Mayan people constructed a large pyramid called 'El Castillo'. 5 When the Spanish came to rule Chichen Itza, they left some of the old buildings.