As well as all your standard planning rules – not accidentally constructing a huge mirror that sets fire to cars if there’s the wrong sort of sun, etc. – London has another unusual consideration for would-be skyscraper builders: you have to ensure you don’t ruin the view of St Paul’s Cathedral.

Some of this concerns the area immediately surrounding it in the City of London, referred to as “St Paul’s Heights”, established in 1937. Within this area, the City’s planning department aims to preserve the existing views of St Paul’s, although there are quite a few buildings that already infringe it – either because they predate the current iteration of planning policy or because, like the new Blackfriars station, they’re not in the City so it couldn’t do anything about it.

No tall things please, we're British. Image: City of London.

But the effect of the cathedral on planning spreads way past the borders of the City: several “viewing corridors” exist to keep St Paul’s visible from other parts of London. The longest, and oldest, runs all the way to King Henry VIII’s Mount in Richmond – far enough way they’ve had to set up a telescope to enable you to see it as much more than a tiny dome-shaped blur. The view of the cathedral is also protected from Parliament and Primrose Hills, although the growth of the skyline around in over the last century means it barely stands out anyway.

The view from Primrose Hill. Find St Paul’s, win a pound. (N.B. You will not win a pound.) Image: Wikimedia Commons/Diliff.

In recent years, there’s been huge pressure to relax some of these rules given the increasing demand for ludicrously shaped tall buildings in London – when Ken Livingstone was mayor, he decreased the size of the “viewing cones” from 440m to 210m – and the sky has, as yet, failed to fall in. Even if you do care about views, the argument could be made that a skyscraper can be as interesting to look at as a cathedral.

The various protected views of London. Image: OpenStreetMap.

While London is notable for having so much planning policy dictated by a single building (although views of parliament and the Tower of London are also protected), it’s certainly not the only city to operate this kind of policy. Quite a few places in the UK have laws that restrict building heights or otherwise protect views around their cathedrals – simply because, like St Paul's, they had been the tallest building in the area for centuries.

In the US, Portland, Oregon has a “Scenic Resources Protection Plan” to manage development, partly inspired by a popular view of the local mountain being ballsed up by the pointy KOIN Center building.

A spectacularly sarcastic section of a planning report. Image: portlandoregon.gov.uk.

While this sort of thing might carry a general sense of worthiness, it is not necessarily without cost. San Francisco’s extremely restrictive planning laws are in part about preserving key views in the city – but they also mean hardly anyone can afford to live there, as demand has massively outstripped the ability to build enough new homes, high density housing being difficult because of the height restrictions.

If nothing else, perhaps there should be an exemption on constructing tall stuff in these areas if there’s a hilariously spiteful reason to do so. The impressive Art Deco Kavanagh building in Buenos Aires was commissioned in 1934 by Corina Kavanagh, an Irish millionaire. According to local legend she’d tried to marry into a local aristocratic family, but the match was rejected because she wasn’t from noble enough stock. In revenge, she bought the land between the family’s mansion, and the fancy local church that they’d paid for, and blocked their favourite view with her new skyscraper.

If there is a lesson here, it’s that if you really want to protect the view of St Paul’s Cathedral, you should have to marry it.

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