4. Sydney Harbour Bridge, Sydney, Australia
The bridge is the largest steel-arch bridge in the world. It's not the longest (that honor belongs to the New River Gorge in West Virginia), but it's one of the most recognizable symbols of Australia. It's 1,149 metres (3,770 feet) long and its arch span is 503 metres.
The top of the arch is 134 metres above the sea and the clearance for shipping under the deck is a spacious 49 meters. Eager to climb to the Pylon Lookout? There are 200 steps to ascend to get to one of Sydney's oldest tourist attractions. If you want to climb it, you can do that too for about $218. In overalls and secured to a safety line, you can climb 1,500 metres over the arch.