The seventh plague was the construction of the great City of Mexico, which, during the early years used more people than in the construction of Jerusalem. The crowds of laborers were so numerous that one could hardly move in the streets and causeways, although they are very wide. Many died from being crushed by beams, or falling from high places, or in tearing down old buildings for new ones. Preconquest Tenochtitlan was built in the center of the inland lake system, with the city reachable by canoe and by wide causeways to the mainland. The causeways were rebuilt under Spanish rule with indigenous labor.