World's Biggest Church
The world's tallest church has taken more than 140 years to build, and today, engineers are nearing completion of Barcelona's Sagrada Familia, designed by maverick architect Antoni Gaudi.
Engineers are building a ground-breaking new railway line in Copenhagen that features 22 miles of tunnels, 17 brand-new stations, and cutting-edge driverless trains.
Venice Storm Wall
Venice's new storm wall is one of the strongest in the world, a 330-ton behemoth that protects the historic city from disastrous flooding.