Our graphic showing how deep London goes caused quite a stir. So here's the sequel, a guide to the tallest structures in London: past, present, future and imaginary. See below for details on each feature.
Tallest residential: The Tower, One St George
This is the cylindrical tower near Vauxhall that looks like a bloated BT Tower. Completed in early 2014, it stands 180.6 metres tall. Its profile dominates the skyline in this part of town, but with many more towers going up, it won't be long before it's just one of a crowd. The title of tallest residential tower block is poised to switch to Canary Wharf in 2020, when the 235m cock-and-balls tower, also known as The Spire, should be completed.
Tallest demolished: Old St Paul's Cathedral
London probably had the tallest structure on Earth for a short time. When completed in the 13th century, Old St Paul's Cathedral soared something like 150m into the air. The spire was felled by lightning 1561, and the rest of the edifice was damaged beyond repair in the Great Fire. It remains, by some distance, the tallest building ever demolished in London.
Tallest hill (north): Stanmore Hill, Harrow
Various plaques and trivia books give the main hill at Hampstead as the tallest in north London, but that's an out of date reference to the old County of London. If we're considering Greater London, there are beefier hills to be climbed. Stanmore Hill, north-west of the tube station, is reckoned to be 152m (or 153m — sources vary), a shade taller than the windmill-topped hill of Arkley in Barnet.
Tallest proposed: Mile High Eco Tower
The wonderful yet preposterous Mile High Eco Tower was proposed in 2008 as a soaring solution to the housing crisis. This ivory tower would have climbed to at least 1,500m, making it almost twice the height of the Burj Khalifa. It remains a metaphorical and literal pipe dream.
Tallest church: St Paul's Cathedral
It's nowhere near as lofty as its predecessor, but Christopher Wren's domed cathedral is a much-loved icon of the city. The tallest spired church, meanwhile, is St Mary Abbott in Kensington, which climbs an impressive 85m.
Tallest hill (south): Westerham Heights
Many people would consider this hill to be in Kent, but it actually sits just inside the Greater London border in Bromley. Diamond Geezer paid a visit in 2014, and has a detailed account.
Tallest under construction: 22 Bishopsgate
One of a slew of new towers rising in the Square Mile, 22 Bishopsgate is both the tallest and blandest. This is the site of the stalled Pinnacle tower, whose core rose to a few storeys before the project was scrapped. The replacement skyscraper will stand 255 metres, making it the tallest building in the City of London.
Tallest tree: Carshalton plane
This is the most uncertain peak in our lineup. The Forestry Commission referred us to a plane tree in Carshalton, which was 37m tall when last measured (1960s). It's tricky to assess tree height accurately, though, and there may well be taller specimens lurking elsewhere.
Tallest building: The Shard
The Shard is not only the tallest building in London, but also the tallest in the European Union (for now). At 244m, its viewing gallery is several floors down from the top, but still comfortably higher than anything else in the capital.
Notes for nitpickers
Different sources quote different heights for tall buildings, as there are several ways of measuring. For consistency, we've used the figures given by CTBUH, the leading authority on international building heights.
By necessity, we've used two measures of height within the diagram. Buildings (and the tree) are measured from ground level, whereas hills are given as height above sea level, which is slightly different. There is no satisfactory way around this. If we were to use height above sea level for buildings, then a tiny house on top of a big hill would be taller than St Paul's. Conversely, it would be meaningless to give a 'height above ground level' for hills.