When you're traveling around the world, it's good to know that there are public transit systems available to help you get where you want to go. Underground subway systems offer the convenience of getting where you want when you want without the hassle of having to flag down a taxi or rent a car. In just about all cases, it's the most cost effective option.

There are some beautiful, modern, and vast rapid transit systems throughout the world. The most popular and diverse international underground transit systems are listed below, but are merely a sample of the quite eye-catching transit systems that exist throughout the world.