Extreme Engineering

A state-of-the-art gas refinery that's being constructed in Spain must be transported over 3,000 miles to the Arctic Circle, and moving this massive structure will prove to be an epic engineering challenge.

Mexico has one of the largest dam building programs in the world, and the biggest is the El Cajon Dam. It will be the highest rock-filled dam in the world, but construction is up against a deadline and they're running out of time.

The Woodrow Wilson Bridge is proving inadequate for the demands of today's traffic. A replacement is being constructed and it's a feat of engineering, featuring seven additional miles of roadway to connect Virginia and Maryland.

The longest cable car lift on Earth is being constructed on Lantau Island, in Hong Kong and it has to withstand landslides and typhoons. It's being built by an elite cable car construction team, but the project is behind schedule.

Ski Dubai aims to offer the dream of snow skiing in the desert, and will be the largest indoor ski resort in the world. Construction crews face the monumental challenge of building this incredible structure on time and on budget.

The Gotthard Base Tunnel will be the longest tunnel in the world, creating rail travel through the Alps. With breakthrough engineering methods, it's undoubtedly one of the most ambitious construction projects ever attempted.