A 24 hour-long video installation showing the time is going on display at Tate Modern.

The gallery will be holding screenings, lasting 24 hours, of the work by London-based artist Christian Marclay.

Described as a “contemporary masterpiece”, The Clock is a montage of thousands of film and TV clips specifying the time of day, synchronised to the exact time where it is screened.

An image from The Clock (Christian Marclay)
An image from The Clock 2010 (Christian Marclay/Courtesy White Cube, London and Paula Cooper Gallery, New York)

Tate said the audience would “experience a vast range of narratives, settings and moods within the space of a few minutes, allowing time to unravel in countless directions at once”.

Tate Modern director Frances Morris said: “The Clock is one of the most exceptional and complex artworks of the 21st century and it is no surprise that, wherever it is shown, the audience is riveted.”

The free screenings will take place for three months from September next year and were announced as Tate unveiled its annual report.

It showed Tate’s latest acquisitions, including Chinese artist Ai Weiwei’s Tree (2010), a sculpture made from dry branches, roots and trunks made to look like one tree.

Tate Modern, London (Tim Ireland/PA)
Tate Modern, London (Tim Ireland/PA)

Tate is also now the owner of Martin Creed’s Work No. 960 (2008) – a row of 13 neatly lined up cacti, each in a terracotta plant pot placed on the floor, arranged in order of height.

Creed – who gave the work to Tate – is praised for taking “an ostensibly unremarkable group of objects and presenting them in an unexpected way”, with his work “concerned with the human impulse to make sense of the chaotic flux of experience”.

Other works acquired by Tate include a collection of photographs by Chris Steele-Perkins from the 1980s, including an image of then prime minister Margaret Thatcher.