18 of the world’s best metro systems

Crowded, hot, noisy, hectic — subway systems can test the sanity of even the most hardened urbanite, but can you imagine the world’s biggest cities without them? And as millions more of us flock to live in cities every year, efficient mass transit is going to become ever more critical to urban life.

Subways – more commonly known as metros outside North America — are as varied as the cities they serve. They encompass everything from claustrophobic Victorian “tube” tunnels cut by hand to elegant turn-of-the-century steel viaducts and hypermodern subterranean cathedrals served by fully automatic trains.

What links them all is their incredible engineering and the role they play in the lives of people and cities. Here are a few of our favorites.