The Union Buildings (Afrikaans: Uniegebou) form the official seat of the South African Government and also house the offices of the President of South Africa. The imposing buildings are located in Pretoria, atop Meintjeskop at the northern end of Arcadia, close to historic Church Square. The large gardens of the Buildings are nestled between Government Avenue, Vermeulen Street East, Church Street, the R104 and Blackwood Street. Fairview Avenue is a closed road through which only officials can enter the Union Buildings. Though not in the centre of Pretoria, the Union Buildings occupy the highest point of Pretoria, and constitute a South African national heritage site.

The Buildings are one of the centres of political life in South Africa; "The Buildings" and "Arcadia" have become metonyms for the South African government. It has become an iconic landmark of Pretoria and South Africa in general, and is one of the most popular tourist attractions in the city and an emblem of democracy.

The Buildings are the location of presidential inaugurations.

These buildings, built from light sandstone, were designed by the architect Sir Herbert Baker in the English monumental style and are 285 m long. They have a semi-circular shape, with the two wings at the sides, this serves to represent the union of a formerly divided people. The clock chimes are identical to those of Big Ben in London. The east and west wings, as well as the twin-domed towers, represent two languages, English and Afrikaans, and the inner court was designed and built to symbolise the Union of South Africa. These buildings are considered by many to be the architect's greatest achievement and a South African architectural masterpiece. The Nelson Mandela statue in Sandton City's Nelson Mandela Square was commissioned originally to stand on the spot where Nelson Mandela gave his inaugural address.

The building was sited on a disused quarry, which now makes up the amphitheatre. The matching statues on top of the domed towers are Atlas, holding up the world, sculpted by Abraham Broadbent. The statue on the domed rostrum in the amphitheatre between the wings is Mercury, a mythic Roman messenger and a god of trade, sculpted by George Ness. The closest suburb to the Union Buildings is Arcadia, which is named after the classical idealisation of the ancient Greek region of the same name . Pretoria has the second largest number of embassies in the world, after Washington, D.C., most of which are located in or near Arcadia.

The design of each level differs, and therefore each stone had to be individually cut. The Architectural styles of the building ranges from the lower levels' Edwardian style to the top levels' Cape Dutch design with shutters on the windows. The windows from bottom to top are elongated and become shorter towards the top floor. This is to give the illusion of height.

The Union Buildings are the site of presidential inaugurations. The official offices of the president are on the left-hand side of the Union Buildings, and the South African national flag is flown on the left-hand side if the president is in office.

The Buildings are divided into three sections; the left offices, amphitheatre, and right offices. All are 95 metres in length. Each office block contains three inner courtyards providing light and air to the offices. Each block has a basement and three floors above ground. The central curved building behind the colonnade houses the committee rooms, a library and conference rooms while the basement contains the kitchen, dining rooms and lounges.