The conquerors proceeded immediately to rebuild the city, native architects chiefly being employed to do the work. Materials for the rebuilding were taken from the ruins; probably many of the old Aztec foundations were retained, and there may now be edifices in the city of Mexico which stand on some of these foundations. Twelve acres of the great inclosure of the Aztec temple were taken for a Spanish plaza, and are still used for this purpose, while the site of the temple is occupied by a cathedral. The plaza is paved with marble. Like the rest of the great inclosure, it was paved when the Spaniards first saw it, and the paving was so perfect and so smooth that their horses were liable to slip and fall when they attempted to ride over it. Some relics recovered from ruins of the old temple have been preserved. Among them is the great Aztec calendar which belonged to it, on which are carved hieroglyphics representing the months of the year. This calendar was found in 1790 buried in the great square. It was carved from a mass of porous basalt, and made eleven feet eight inches in diameter. It was a fixture of the Aztec temple; it is now walled into one side of the cathedral. The “stone of sacrifice,” another relic of the temple, nine feet in diameter, and covered with sculptured hieroglyphics, can still be seen in the city, and in the suburbs, it is said, vestiges of the ruins of long lines of edifices can be traced. Calendars made of gold and silver were common in Mexico. Before Cortez reached the capital, Montezuma sent him two “as large as cartwheels,” one representing the sun, the other the moon, both “richly carved.” During the sack of the city a calendar of gold was found by a soldier in a pond of Guatemozin’s garden. But these Spaniards did not go to Mexico to study Aztec astronomy, nor to collect curiosities. In their hands every article of gold was speedily transformed into coin.