London once had a driverless underground railway built just for mail!Opened in 1927, the 10.5 km network connected major sorting centres beneath the city. It fi

London once had a driverless underground railway built just for mail!Opened in 1927, the 10.5 km network connected major sorting centres beneath the city. It finally closed in 2003 due to high costs but parts of it still survive today [▻](https://video.twimg.com/amplify_video/2090849493591695360/v…