A pyramid has been installed at the Speaker's Corner in Hyde Park to precede an exhibition of artefacts of Egyptian boy-king Tutankhamun.
About 1,500 children participated in designing the 45-ft pyramid
The 45ft hand-painted structure was created and designed by Brazilian pop artist Romero Britto.
The artwork was created to mark the opening of Tutankhamun And The Golden Age Of The Pharaohs at the O2 Bubble.
Students from the UK, the US, Egypt, Belgium and France worked on the piece along with the artist.
Mr Britto said: "I am both honoured and humbled by the opportunity to install my artwork in one of the world's most famous locations, Speakers' Corner at Hyde Park."
The artist also thanked 1,500 children who contributed to two sides of the pyramid during an international arts project in July and left "their own artistic impression" on the sculpture.
The Tutankhamun exhibition will be the first to be held at the O2 Bubble venue, and about 325,000 tickets have already been sold.
The artist also created a 25ft-high pyramid, which will be placed outside O2 arena, and eight other 8ft-high pyramids which will be installed at different locations in the city for the duration of the exhibition.
The ancient artefacts will return to London after a gap of 35 years.
It will run from 15 November 2007 to 30 August 2008, and showcase more than 130 Egyptian treasures dated from 3,000 to 5,000 years ago.
After the exhibition, the main 45ft pyramid will be displayed outside a children's museum in the Egyptian capital, Cairo.