London bollards

knowledgeoflondon.com
"The original street bollards became adapted from the French cannons captured at the battle of Trafalgar in 1805. They were placed on street corners to stop the iron wagon wheels of carts from mounting the kerbs and doing damage. They proved so popular that they adorned many of the London streets and, once the real Cannons were all used up, copies were made and are still to be seen on the streets of London today."