Lange Leopold Powell (1886–1938) was a noted architect who designed many important buildings in Brisbane and the state of Queensland. He started practice in 1909; his major works included St Martin's War Memorial Hospital and the Masonic Temple, Brisbane (1928)

St Martin's House is a heritage-listed former private hospital and now administration building within the grounds of St John's Cathedral at 373 Ann Street, Brisbane City, City of Brisbane, Queensland, Australia. It was designed by Lange Leopold Powell and built c. 1922 by Thomas Keenan. It is also known as St Martin's Hospital. It was added to the Queensland Heritage Register on 21 October 1992.