London is a big, sprawling metropolis that has changed and evolved over many hundreds of years. And that means it’s hiding plenty of secrets.

This video reveals one of those secrets, which is the fake houses that adorn some streets. Why? To hide the London Underground.

The early lines were built using cut and cover, which meant buildings had to be demolished. But to keep the posh street looking as it should, facades were constructed.

These days, boring machines tunnel underground, so the old cut and cover method isn’t needed. Which is a good job for anyone who owns a house in London.