than any structure built in human history until the construction of the Eiffel Tower in 1889, which is in height. Gregory of Tours writing c. 594, quotes the earlier historian Orosius (c. 417) as saying the tower was "laid out foursquare on a very level plain. Its wall, made of baked brick cemented with pitch, is fifty cubits (23 m or 75 ft) wide, two hundred (91.5 m or 300 ft) high, and four hundred and seventy stades (82.72 km or 51.4 miles) in circumference. A stade was an ancient Greek unit of length, based on the circumference of a typical sports stadium of the time which was about . Twenty-five gates are situated on each side, which make in all one hundred. The doors of these gates, which are of wonderful size, are cast in bronze. The same historian tells many other tales of this city, and says: 'Although such was the glory of its building still it was conquered and destroyed.'" A typical medieval account is given by Giovanni Villani (1300): He relates that "it measured eighty miles [130 km] round, and it was already 4,000 paces high, or and 1,000 paces thick, and each pace is three of our feet." The 14th-century traveler John Mandeville also included an account of the tower and reported that its height had been 64 furlongs, or , according to the local inhabitants. The 17th-century historian Verstegan provides yet another figure – quoting Isidore, he says that the tower was 5,164 paces high, or , and quoting Josephus that the tower was wider than it was high, more like a mountain than a tower. He also quotes unnamed authors who say that the spiral path was so wide that it contained lodgings for workers and animals, and other authors who claim that the path was wide enough to have fields for growing grain for the animals used in the construction. In his book, Structures: Or Why Things Don't Fall Down (Pelican 1978–1984), Professor J.E. Gordon considers the height of the Tower of Babel. He wrote, "brick and stone weigh about 120 lb per cubic foot (2,000 kg per cubic metre) and the crushing strength of these materials is generally rather better than 6,000 lbs per square inch or 40 mega-pascals. Elementary arithmetic shows that a tower with parallel walls could have been built to a height of before the bricks at the