The Sydney Opera House is an expressionist modern design, with a series of large precast concrete 'shells', each taken from a hemisphere of the same radius, forming the roofs of the structure. The Opera House covers 1.8 hectares (4.5 acres) of land. It is 183 metres (605 ft) long and about 120 metres (388 ft) wide at its widest point. It is supported on 588 concrete piers sunk up to 25 metres below sea level. Its power supply is equivalent for a town of 25,000 people. The power is distributed by 645 kilometres of electrical cable.

The roofs of the House are covered with 1,056,006 glossy white and matte cream Swedish-made tiles, though from a distance the tiles look only white. Despite their self-cleaning nature, they are still subject to periodic maintenance and replacement.

The Concert Hall is contained within the western group of shells, the Opera Theatre within the eastern group. The scale of the shells is chosen to reflect the internal height requirements, rising from the low entrance spaces, over the seating areas and up to the high stage towers. The minor venues (Drama Theatre, Playhouse, and The Studio) are located beneath the Concert Hall, as part of the western shell group. A much smaller group of shells set to one side of the Monumental Steps houses the Bennelong Restaurant. Although the roof structures of the Sydney Opera House are commonly referred to as shells (as they are in this article), they are in fact not shells in a strictly structural sense, but are instead precast concrete panels supported by precast concrete ribs.

Apart from the tile of the shells, and the glass curtain walls of the foyer spaces, the building's exterior is largely clad with aggregate panels composed of pink granite quarried in Tarana. Significant interior surface treatments also include off-form concrete, australian white birch plywood supplied from Wauchope in northern New South Wales, and brush box glulam.

Performance venues and facilities

The Concert Hall and Grand Organ

The Sydney Opera House contains five main performance spaces, other areas used for performances, a recording studio, five restaurants, and four souvenir shops.

The five venues making up the main performance facilities:

The Concert Hall, with 2,679 seats, is the home of the Sydney Symphony, and used by a large number of other concert presenters. It contains the Sydney Opera House Grand Organ, the largest mechanical tracker action organ in the world, with over 10,000 pipes.

The Opera Theatre, a proscenium theatre with 1,507 seats, is the Sydney home of Opera Australia and The Australian Ballet.

The Drama Theatre, a proscenium theatre with 544 seats, is used by the Sydney Theatre Company and other dance and theatrical presenters.

The Playhouse, an end-stage theatre with 398 seats.

The Studio, a flexible space, with a maximum capacity of 400 people, depending on configuration.

Other spaces used for performances and other events include:

The Utzon Room , a small multi-purpose venue, seating up to 210. It is the only interior space to have been designed by Utzon, having been renovated in 2004 under his direction.

The Forecourt, a flexible open-air venue with a wide range of configuration options, including utilising the Monumental Steps as audience seating, used for a range of community events, Live Sites, and special-occasion performances.

Besides theatrical productions and concerts, venues at the Sydney Opera House are also used for activities such as conferences, ceremonies, and social functions.