Hyde Park Obelisk, Sewer vent obelisk in Hyde Park, Sydney, Australia

The Hyde Park Obelisk is a 22-metre-high masonry shaft at the corner of Elizabeth and Bathurst Streets, with a square sandstone base 6.5 metres tall and a filigreed bronze pyramidion at the top. Completed in 1857 in the Victorian Egyptian style, it was modelled on Cleopatra's Needle in London and served as an educt vent for Sydney's first planned sewerage system.

It was built in 1857 under Mayor George Thornton's direction as part of Sydney's first planned underground sewerage network. The structure represents an early engineering response to managing waste in a growing city.

Local residents call it Thornton's Scent Bottle because of how it releases sewer gases above street level through its design. The Egyptian-style decorations reflect Victorian fascination with exotic architectural elements.

The obelisk sits at the eastern end of Hyde Park and is accessible throughout the day to pedestrians exploring the area. It serves as a helpful landmark when navigating the park and surrounding streets.

On 7 November 2014 the obelisk was fitted with a giant pink condom as a temporary installation raising awareness of HIV, mainly in Sydney's LGBTIQ community. It is also the only sewer ventshaft in the Sydney Water system built entirely of sandstone.