Tulum's North wall and watchtower. Tulum is protected by a wall that averaged about 3–5 meters (9.8–16.4 ft) in height. The wall also was about 8 m (26 ft) thick and 400 m (1,300 ft) long on the side parallel to the sea. On the southwest and northwest corners there are watch towers, showing again how well defended the city was. There are five narrow gateways in the wall with two each on the north and south sides and one on the west. Near the northern side of the wall a small cenote provided the city with fresh water. It is this impressive wall that makes Tulum one of the most well-known fortified sites of the Maya.