Ever wonder what $315-billion worth of gold bars looks like? Well, look no further than this video, which takes you inside a vault owned by the Bank of England. It’s located beneath the City of London, covers a floor space greater than that of the second-tallest building in the City, Tower 42, and needs keys that are three feet long to open. Continue reading for the video and more information.

For those who aren’t familiar with the Bank of England, they are the custodian to the official gold reserves of the United Kingdom and many other countries. They are the fifteenth largest custodian of gold reserves, holding around 4600 tonnes. These gold deposits were estimated in February 2012, to have a current market value of £156,000,000,000.