Q1 (meaning Queensland Number One) is a supertall skyscraper located in Surfers Paradise, on the Gold Coast. It lost its title as the world's tallest residential tower to the 348 metre building The Marina Torch in Dubai on 29 April 2011. As of December 2011[update] it is the fifth tallest such building. Q1 is the tallest building in Australia and the Southern Hemisphere when measured to the top of its spire (second tallest building behind Eureka Tower in Melbourne, when measured to roof and highest habitable floor) and the second-tallest free-standing structure in the Southern Hemisphere, behind Auckland's Sky Tower. It opened in November 2005.
The landmark building was recognised as one of Queensland's icons during the state's 150th birthday celebrations. Q1 has been identified as a potential terrorism target for the region. For a short period of time, an apartment in the building, which was bought for A$9 million by a Japanese restaurateur, was the most expensive ever paid for in Queensland.
At 322.5 m (1,058 ft) and with a roof height of 275 m (902 ft), Q1 qualifies as the world's fifth tallest all-residential building when measured to the top of its structural point (spire), but is ranked lower behind buildings including The Torch at 348 metres in Dubai and Melbourne's Eureka Tower (roof height of 297.28 metres (975.3 ft)) when measured to its roof height and highest inhabitable floor. However, according to the ranking system developed by the US-based Council on Tall Buildings and Urban Habitat, the main criterion by which buildings are ranked is the height of the top of the spire, qualifying Q1 as the taller.