London, England: London Wall

It's still a bit of a shock. Rome is a long way from London today. Imagine how far it must have seemed almost 1,800 years ago. 

Yet the Roman Empire did extend all the way up to England. You only need to look around to see signs of it in modern-day London.

For example, the London Wall, was a defensive structure in the city that was called Londinium. It went up around the year 200, was part of something of a defense network. When the Romans finally left around 400, the wall fell into something of disrepair. By the 1700s, London was busy expanding its limits and didn't want to worry about something like an old wall, so large portions were removed.

Still, there are parts of it left, and restoration efforts continue. The Eastern portion of the Wall begins around the Tower of London. That's Emperor Trajan (98 to 117 A.D.) waving hello near the subway stop.