London is the capital city of the United Kingdom.

Greater London covers an area of 609 square miles (1,579 square km). London is a port on the Thames, a navigable river. The river has had a major influence on the development of the city. London began on the Thames' north bank and for many centuries London Bridge was the only bridge in or close to the city. Because of this the main focus of the city was on the north side of the Thames. When more bridges were built in the 18th century, the city expanded in all directions as the mostly flat or gently rolling countryside presented no obstacle to growth.

Rivers and canals

The Thames was once a much broader shallower river than it is today. It has been extensively embanked, and many of its London tributaries now flow underground. The Thames is a tidal river, and London is vulnerable to flooding. The threat has increased over time due to a slow but continuous rise in high water level and the slow 'tilting' of Britain (up in the north and down in the south) caused by post-glacial rebound. The Thames Barrier was constructed across the Thames at Woolwich in the 1970s to deal with this threat, but in early 2005 it was suggested that a ten mile long barrier further downstream might be required to deal with the flood risk in the future [1].

Rivers

• The River Thames
• The River Brent
• The River Cray
• The River Lee (or River Lea)
• The River Ravensbourne (tidal reach known as 'Deptford Creek')
• The Wandle
• The New River

Subterranean rivers

• The Langbourne (dubious)
• The Walbrook
• The River Fleet
• The Tyburn
• The Tyburn Brook
• The River Westbourne
• Counter's Creek
• Stamford Brook
• The River Neckinger
• The River Effra

Canals

• Grand Union Canal
• Regent's Canal
• The River Lee Navigation
• The Croydon Canal

Islands in the Thames

Note: Only the largest islands are listed here. A longer list can be found in the River Thames article.

• Canvey Island
• Isle of Grain
• Isle of Dogs
  • Millwall
  • Cubitt Town
  • Blackwall
• Eel Pie Island

Climate

London has a temperate climate, with warm but seldom hot summers, cool but rarely severe winters, and regular but generally light precipitation throughout the year. Summer temperatures rarely rise much above 33°C (91.4°F), though higher temperatures have become more common recently. The highest temperature ever recorded in London was 38.1°C (100.6°F), measured at Kew Gardens during the European Heat Wave of 2003. Heavy snowfalls are almost unknown. In recent winters, snow has generally only settled once or twice and it is rarely more than an inch (25 mm) or so. London's average annual precipitation of 584mm (22.9 inches) is lower than that of Rome or Sydney. London's large built up area creates a micro climate, with heat stored by the city's buildings. Sometimes temperatures are 5°C (9°F) warmer in the city than in the surrounding areas.

The following table shows average climate date for 1971-2000 at the Met Office station at Greenwich which is the closest station to the centre of London.

Hills

The hills in the City of London, Ludgate Hill to the west and Tower Hill further east, are presumed to have influenced the precise siting of the early city, but they are very minor, and most of central London is almost flat. There are a few notable hills in Greater London, but none of them more than a few hundred feet high, and they have not impeded the development of the city in all directions. It is therefore very roughly circular.

• Greenwich Hill
• Hampstead Hill
• Horsendon Hill
• Ludgate Hill
• Muswell Hill
• Parliament Hill, London
• Primrose Hill
• Shooters Hill
• Tower Hill
• Tyburn Hill