The Hyde Park Obelisk is an obelisk located on the western edge of Hyde Park. This monument, which was unveiled in 1857 by the Lord Mayor, George Thornton, was originally used as a sewerage vent, so was jokingly referred to as Thorton's Scent Bottle. It was built at the junction of Elizabeth Street and Bathurst Street because the sewage system was at its highest point here, although it is no longer used as a vent to avoid the risks of contamination. The monument is 22 metres high, including the 6.5 metre high square sandstone base and a filigreed bronze pyramid vent at the top. This obelisk was modelled on Cleopatra's Needle, on the banks of London's Thames River.