London is the capital and most populous city of England and
the United Kingdom. Standing on the River Thames in the south east of the island of Great Britain, London has been a major settlement for two millennia. It was founded by the Romans, who named it Londinium. London’s ancient core, the City of London, largely retains its 1.12-square-mile (2.9 km2) medieval boundaries. Since at least the 19th century, “London” has also referred to the metropolis around this core, historically split between Middlesex, Essex, Surrey, Kent and Hertfordshire, which today largely makes up Greater London, a region governed by the Mayor of London and the London Assembly.
The agglomeration has grown far beyond those borders since Victorian times, though a significant suburban or commuter belt extends as far as 20 miles (32 km) from Charing Cross; small parts extend even further outwards into Essex to Thurrock in one direction (which actually now falls under Greater London’s jurisdiction), Northampton in another, while other areas included within Greater London are not contiguous with it but rather form large loops surrounding it such that almost all of them are reachable within an hour’s journey by public transport from central areas. The vast majority of this land area is green space; just over half being parks, open spaces or playing fields.:8 In 2019 there were more than nine million trees across Greater London both in street tree planting schemes and private gardens representing about 33% tree cover.:19 With few exceptions – mainly along roads where they have been felled for safety reasons – trees are protected under law through TPOs (Tree Preservation Orders).:20 Trees can grow to a considerable size within urban areas where there is sufficient space: many common ash (Fraxinus excelsior) exceed 30 m (98 ft) when mature while some plane trees planted as partway features along streets have reached 40–50 m (130–160 ft).