By 2900 B.C , the Egyptians were sailing to Byblos in lebanon to buy cedarwood for shipbuilding. These ships had a large square carried on a double mast, which could be lowered when the ship was being rowed, and were steered by oars. Imported timber enabled the Egyptians to build giant barges to move long and heavy stone obelisks along the Nile. The biggest of these barges (about 1500 B.C.) were 61 meters (200 feet) long by 24 meters (80 feet) across. Able to carry 700 tons, they were towed by 27 smaller craft.