The Roundel is super famous and very recognisable, I bet you've seen it yourself before! But what is it? Let's find out all about it with some help from London Transport Museum.

Marina Ventura and The Micro-Gridders: The Super Squad
05:17

The Circular Trail: a free Time Hunters history walk around the City of London
46:10

Marina Ventura and The Micro-Gridders: The Power Stash
05:25