The aggressive Toltecs conquered the Itzas, introduced them to the practice of human sacrifice and with their labor rebuilt the city as a religious centre.
Everyone moved out by the thirteenth century, so when the Spaniards came in the 1500s they found crumbling buildings being devoured by the greedy jungle.
A New York lawyer rediscovered them in 1842, following which an influx of amateur archeologists destroyed some.
Real restoration and reconstruction by the Carnegie Institute and Mexican government was begun in 1922, and continued for 20 years.