In 1781 The Bank of England became the bankers' bank and was required to keep enough gold in reserves to pay all its issued notes on demand, a promise still printed on every bank note today.
The Bank's original home was in Walbrook moving to its current location on Threadneedle Street in 1734. The present building, covering 3.5 acres, stands on an island site surrounded by huge walls. The underground vault, which contains more space than a large office block, holds gold reserves of the UK and many other countries making it one the largest stocks of gold bullion in the world.