The Powerhouse Museum is the major branch of the Museum of Applied Arts and Sciences in Sydney, the other being the historic Sydney Observator.The Powerhouse Museum is the major branch of the Museum of Applied Arts and Sciences in Sydney, the other being the historic Sydney Observatory. Although often described as a science museum, the Powerhouse has a diverse collection encompassing all sorts of technology including Decorative arts, Science, Communication, Transport, Costume, Furniture, Media, Computer technology, Space technology and Steam engines.