Machu Picchu is one of the worlds top tourist attractions and officially a world heritage site. Further the trek to Machu Picchu is one of the best.
Uluru (Ayers Rock) is a world heritiage site, and to walk around it is a special experience.

One of Sydney's top experiences is 'climbing' (more like walking) the Sydney habour bridge. From the bridge you have amazing views of one of the most impressive habours on the planet.
Book. Turn up, put on the gear, and do the drill. The 'express climb' requires 2.25 hours, while the 'standard' (discovery) climb requires 3.5 hours.
The climb can be done at 4 different times of the day.
