A Walk Of Steel

Where: Sydney, Australia

No other bridge in the world offers this kind of adult playground. The Sydney Harbour Bridge has been an icon ever since it was completed in 1932. But it didn't become an adventure destination until 1998 when the BridgeClimb was created for folks who couldn't get enough of the structure simply by driving, riding the train, or walking across it.

Today, there are two ways to get a closer look at the bridge's intricacies and even reach its highest point. Opt for the Discovery Climb, which offers a longer and more challenging route into the heart of the bridge rather than over it. Until 2006, only maintenance workers had access to many of the pathways that you can now walk across during this 3½ hour urban hike. As you ascend the steep staircases and ladders, winding through hatchways and girders suspended high above speeding cars and buses below, your guides will discuss the Harbour Bridge's history through radio headsets attached to the shapeless grey jumpsuit that you're forced to wear. Among other things, it includes a device that attaches you to a safety cable and provides a waterproof cover in case it rains. With these provisions and your well-trained leader, the ascent itself is perfectly safe. But it can feel completely daunting at times, especially when the wind blows and traffic races below you.

As you continue heading skyward, you'll pass the point where the arches of the bridge were originally joined in 1930. When you reach the metal mountain's peak, you can actually go between the arches that are 134m (440 ft.) above the water. As you touch the raw steel and strong rivets holding things together here, try not to let this awe-inspiring feat of engineering knock you off balance. Take a deep breath and look around at the panoramic views of Sydney -- complete with ships in the harbor, the opera house, and skyscrapers far below your feet. If it's midday, you'll see the city buzzing with daily activities. Early risers can climb the bridge at dawn and watch the sunrise. Romantics can try it at twilight. No matter what time you're up here, it's clear that this is one of the world's most unforgettable city walks.

Information: Sydney Harbour BridgeClimb (tel. 61/02-8274-7777; www.bridgeclimb.com).

When to Go: Anytime.

Getting There: Sydney airport.

Where to Stay: Park Hyatt Sydney, 7 Hickson Rd., The Rocks (tel. 61/02-9241-1234; www.sydney.park.hyatt.com). BLUE Sydney, 6 Cowper Wharf Rd. (tel. 61/02-9331-9000; www.tajhotels.com/sydney).