Technical background

The job of converting the Baltic Flour Mills into Britain's newest national gallery took three years in two stages.

First, contractors Nuttalls hollowed out the interior of the building, which was a mass of 180 concrete and steel grain silos. The only parts of the original building  kept were the north and south walls and four brick corner towers.

The 10 month job started in July 1998 when the contractors put up a 650 tonne steel frame around the building, which kept the walls standing while the inside of the building was hollowed out.

The roof and top floor was then ripped off by diggers which had to be craned on and off the building. The brick end walls were then cut away from the rest of the building and pulled down to allow diggers equipped with concrete crushing "nibbler" arms to tear out the interior silos.

More than 5,000 cubic metres of concrete and rubble were removed before the second stage of the job to install 13 concrete floors. The main gallery floor is  strong enough to support 6 tonnes - which would enable an artist to do something like flood the floor a metre deep with engine oil.

Lifts capable of taking a 40 tonne lorry up the building were installed at the east end of the building, and massive sliding access doors replaced the demolished wall to allow even the largest art works to be craned in.

A glass wall and lifts were installed at the west end, overlooking the Tyne Bridge, and a new, two-story glazed riverside building built as the main entrance to the Baltic.

The entrance was panelled with Corten steel - the same as used to build the Angel of the North. It also includes a bookshop, cafe, information centre and main reception area. A bright, airy main staircase and elevators provide rapid and easy access for the public to the upper floors.