The cathedral has the tallest church spire in the United Kingdom (123m/404 ft). Visitors can take the 'Tower Tour' where the interior of the hollow spire, with its ancient wood scaffolding, can be seen. The cathedral also has the largest cloister and the largest cathedral precinct ('close') in Britain (80 acres). The Cathedral contains the world's oldest working clock (from AD 1386). It also has one of the four surviving original copies of the Magna Carta (all four original copies are in England). 