Discover Sydney Opera House

The building's roof is made up of a series of precast concrete shells, arranged like giant overlapping sails, that were among the most technically difficult structures ever attempted at the time -- Utzon's original freehand sketches took years of engineering work with Ove Arup and Partners before a workable structural solution, based on sections of a single sphere, was found.

More than a million glazed ceramic tiles, made in Sweden, cover the shells in a subtle two-tone pattern of glossy white and matte cream -- from a distance the roof reads as pure white, but the texture becomes visible up close.

Inside, the building holds multiple performance venues beneath the shells, including the Concert Hall and the Joan Sutherland Theatre, along with a recital hall, a drama theatre, and a studio space -- a complex interior arrangement that had to be fitted within a roof form designed before the building's internal functions were fully settled.

Jørn Utzon resigned from the project in 1966 amid disputes over cost and design control, and never saw the completed building in person -- the interiors were substantially redesigned by other architects after his departure, a point of long-running debate among architecture historians about how closely the finished building matches his original vision.