A huge "black hole" was unveiled today as the latest exhibition at the Tate Modern.
The steel sculpture, resembling a giant shipping container, has been placed in the building's Turbine Hall.
Visitors can enter the chamber, which compares with the length of a few buses at 98ft (30m) long, 43ft (13m) high and 33ft (10m) wide.
The sculpture is the 10th annual commission in Tate's Unilever Series.
Titled How It Is, the work is by Polish artist Miroslaw Balka.
It is raised 6ft 6in (2m) off the ground so that visitors can wander underneath before walking up a ramp and entering the pitch- black container.
Footsteps echo inside the black void, which is lined with a soft fuzzy coating.
The title of the installation is inspired by Samuel Beckett's novel How It Is.
Balka said: "You can shape this yourself. The shape you create is not just about your body, it's about your mind."
The annual Unilever commission invites artists to make a work of art especially for Tate Modern's Turbine Hall, leading to big bold installations which have been loved by some and ridiculed by others.
Previous installations in the series have included a giant crack stretching the length of the cavernous space, by Doris Salcedo, and Turner Prize winner Rachel Whiteread's creation, a labyrinth comprised of 14,000 casts of boxes.
A series of spiralling slides by German artist Carsten Holler sent 750,000 visitors whizzing through the gallery.
Previous works by Balka include a collection of used bars of soap.
His works often explore themes of personal history, set in his native Poland, sometimes referring to the Holocaust.
It was put to Balka at a press conference at the Tate Modern that his giant container could refer to ideas of human trafficking as well as the Holocaust.
He said there was no single direct inspiration for the piece, adding: "It's everything and nothing in a way... when I decided to make the sculpture I really did not know what the sculpture was about."
Asked how he felt on stepping inside for the first time himself, he said: "I used the word 'Whoa' - it works. I did not have this moment of not being prepared... a moment of happiness came to me, it was not about fear any longer."
Exhibition organisers said gallery attendants would be on hand and would supply torches if necessary in case visitors do not react well and feel panicky about being inside the space.
Balka said he came up with the title for the work after coming across Beckett's book in a shop.
"Before, we had been discussing the title Negative," he said, adding that the new title was much wider and more open.
Questions were put at the press conference about more recent Unilever commissions having gloomy themes.
Balka said: "The 21st century - it's not so happy as we could suppose, so that's how it is."
The installation can be seen by the public from October 13 to April 5, 2010.