115 King William Street, Modern office building in Adelaide, Australia.

115 King William Street is a 26-storey office tower on the west side of King William Street, between Waymouth and Currie streets in central Adelaide. It rises 87 metres to the roof and 91 metres to the antenna spire. Construction began in 2015 and was completed in 2016.

Planning approval came initially for a smaller building in 2010, but the design was later expanded into the taller structure completed in 2016. This expansion reflected growing commercial demand in Adelaide's city center during that decade.

The building stands on a site that transformed from a nineteenth-century solicitor residence to Commercial Union Chambers before becoming the current structure.

The building sits between Waymouth and Currie streets in a well-connected location that is easy to reach by public transport or car. The surrounding area offers parking options and good access to other parts of the city center.

The address has hosted commercial offices since the nineteenth century, when it was the office and home of solicitor George Michell. From the 1930s it was associated with the printing firm Scrymgour & Sons. The current tower was approved in July 2010 at only 64 metres and 16 storeys, then raised to 25 floors and, in August 2015, to 26.