Largest Metro Systems You Want to Visit

London Underground

As the oldest metro system in the world the London Underground has track dating back to 1863. It serves 270 stations over 250 miles of track. (“The Tube”), London, England – 270 stations – The first electric line opened in 1890 making it the world’s very first metro system. It’s also the third longest system with 402 km and more than 1.2 billion users each year.