Ian Thorpe Aquatic and Fitness Centre, Public aquatic center in Ultimo, Sydney, Australia.

The Ian Thorpe Aquatic and Fitness Centre is a public sports facility with three swimming pools, modern exercise equipment, and training areas inside a wave-shaped building. The venue contains separate water zones and fitness spaces designed to serve swimmers and fitness enthusiasts of all levels.

In 2000 the city launched a competition for the Ultimo Aquatic Centre; after about 100 entries the open contest was scrapped and three firms were invited, with Harry Seidler's chosen in late 2001. Budget disputes stalled the project until 2004, when Clover Moore's council backed the full $40 million plan over a $25 million alternative. Seidler died in 2006; his widow Penelope oversaw completion and the centre opened in August 2007.

The centre is named after Ian Thorpe, the Australian Olympic swimming champion, after the project was renamed in his honour. Its 2009 International Architecture Award and the 2013 listing by critic Elizabeth Farrelly among Sydney's five best buildings made it a reference point for Seidler's late work.

The centre sits in Ultimo, a short walk from the Ultimo Road end of the city centre, and is co-managed by the City of Sydney and Belgravia Leisure. Its three pools and fitness areas are spread across the interior of Harry Seidler's curved building, so allow time to find the undefined entry and the narrow changing spaces noted by critic Elizabeth Farrelly.

The building's distinctive curved roof was Harry Seidler's final architectural work and received an international architecture award in 2009. The wave-like shape makes it recognizable from many angles in the area.