The Xi’an City Wall is the most intactancient city wall of any in China, enabling visitors to walk its length in acomplete circle.  The original walls were built during the Tang Dynasty(618-907), and were fortified centuries later during the Ming Dynasty.  The wallnow stands 12m (almost 40ft) high, 12-14m (40-45ft) wide at the top, and 15-18m(49-59ft) wide at the base.  The wall wraps around the old city for 13.7km (8.5mi) with a moat running around its outer edge.  Ninety-eight ramparts arestrategically spaced so that the next tower is never beyond arrowshot.  The wallhas only needed restoration three times in its history, the most recentrestoration taking place in 1983.  The wall is also the site of an annualinternational marathon.