Tube geekery

"Secrets of the Circle Line" will feed you public transport trivia ... and make the next journey on the "yellow line" a little more in-depth. And once you've watched that, hop over to one of the other tube lines.

An excerpt:  homage to the  roundel on a drainpipe at 55 Broadway, built as the headquarters of what is now called London Underground -

On completion, it was the tallest office block in London - and what, after all, can be taller than an office block?