For those that dare there is a climb over the Sydney Harbour Bridge, which is one of the most recognizable structures in the world and iconic to Sydney. The climb offers unique stunning views of the city, the Harbour and beyond, but is not for the faint hearted. It is a must for Sydney.

The bridge is a huge steel arch spanning over 500 meters and at its height is 134 meters above sea level. It carries 8 lanes of traffic, 2 railway lines and a footpath and cycle way.

The Sydney Harbour bridge climb is more of a challenge for those without a head for heights, as a large amount of the climb is on narrow steel mesh pathways suspended high in the air above either traffic or water. However, the reward is exhilarating views, and a unique perspective of a beautiful city set on the world’s largest natural harbor. Only moderate physical fitness is required for the climb.

The company that operate the bridge climb are called Bridge Climb Sydney, and have a useful website at www.BridgeClimb.com where they have all the usual information on the climbs available, bookings and costs. A standard climb will cost you about $200, and is money well spent. There are different times of climb available, daytime or night, twilight and dawn. Be aware that the prices rise slightly for the non standard times.

The climb starts in the Rocks, at the south end of the bridge, and climbers will ascend the summit from the south side having made their way up on the east side of the bridge on the Opera House side, then cross over and descend back to the Rocks on the west side of the bridge. The climb is well organized in groups of around 10 persons with a guide. Climbers are attached by a line to a wire running along the path and the guide gives a running commentary.

The company provides all that you need for the climb for safety reasons. At the base at 5 Cumberland St, The Rocks, you check in and then remove everything from your pockets and then lock it all away. Overalls are provided and hats, gloves and even cord to hold your sunglasses on. The company is extremely conscious that there is traffic below so nothing can be dropped. As such all items provided are clipped on to the overalls.

A climb last about three and a half hours and does involve quite a few steps. You get to spend some time at the summit. There are two climbs available, the Bridge Climb and the Discovery Climb. The Bridge Climb ascends and descends on the upper overarching girder, offering spectacular views of the city throughout. The Discovery Climb ascends and descends on the lower overarching girder, offering both the views out to the city but also more of a view into the bridge itself, and its mighty construction. The Discovery climb does ascend to the summit the same as the Bridge Climb, just with a slightly different perspective.

Officially known as Port Jackson, Sydney Harbor reaches 20km (12mi) inland, where it joins the mouth of the Parramatta River. But on the ocean side of the harbor is a much more interesting sight: the Sydney Harbor Bridge.

Completed in 1932, the bridge is unquestionably one of the most famous of that famed city's landmarks. Coming in the middle of the Depression, which was world-wide not merely in the U.S., it was an economic as well as an engineering marvel.

Prior to the bridge the only routes between the center of Sydney in the south and the outlying residential areas in the north were by ferry or a 20km road. The road route required traversing five bridges.

Known locally by some as 'the coat hanger', it is a double-arch style, anchored on both sides of the harbor, with a flat road running beneath the arches. Arches are tied together with short trusses, forming a strong and attractive web. Like many bridges, it brilliantly combines esthetic beauty and technical ingenuity.

Among its many clever aspects is a hinging mechanism at each end that allows the steel structure to expand and flex without cracking. Due to thermal expansion the peak of the arch changes by as much as 18cm/7in. Turning the Golden Gate on its head, so to speak, the roadway runs under the arches, not above them.

Construction began at the end of 1926, with foundations 12m (39ft) deep, set in sandstone, and the arch spans 503m (1650ft). Not the world's longest single arch bridge, even at the time, it is one of the most beautiful, owing to its elegant simplicity and the setting.

Thanks to the six million rivets and the 58,000 tons of steel it is, however, one of the heaviest of its kind. In order to test the load bearing capacity, nearly 100 locomotives were positioned along the roadway in 1932.

By today's standards the 6.25 million Australian pounds ($12.5M) construction cost seems modest, but at the height of the Depression it was a substantial sum. It was paid off - by tolls that started at 6 pence (5 cents) and even now is only $3 - only in 1988. Today, more than 150,000 vehicles, which once included horses, cross the bridge daily.

The structure includes a lookout point, called Pylon Lookout, from which visitors can see the magnificent harbor, including the much newer Sydney Opera House.

But for those who want a real workout, consider joining the Bridge Club for a stroll. Thanks to the Bridge Club, founded in 1998, visitors can don suitable clothing and, tied to a safety line, actually walk over the arch above the roadway. The view is breathtaking. For the truly bold, there are even night climbs.

Entry is via the pedestrian walkway, reached via stairs from Cumberland Street at the edge of The Rocks. With some 200 steps to the lookout, visitors should be prepared for a healthy climb.