An article by Duncan Geere for Wired.co.UK:
A Russian construction company called AB Elise hopes to build a gigantic domed city in an abandoned diamond mine in Siberia, powered by the sun. The project is more of a concept than a reality so far, but the plans show accomodation for 100,000 people over three main levels.
The mine in question is the Mir mine in the Mirniy industrial zone in Eastern Siberia. You might have probably seen photos of it before, labelled "the largest man-made hole on earth" or something similar. It's long been used to mine diamonds, but the mining stopped in June 2001, replaced with a network of underground tunnels below. Presumably this activity would have to cease if the structure is ever built.
The project, which is described in a series of slides on AB Elise's site, is split between three levels, penetrated in the centre by a vertical farm and forests. Around the exterior are residences and recreational areas, and there's also a research centre in the plans.
However, it might be a tricky construction project -- the climate of the region isn't welcoming -- the ground is permafrost for seven months of the year, and becomes sludge in the summer. Surrounding buildings are mounted on piles so they don't sink. In the winter, temperatures in the area drop down to around -40 degrees celsius.
What the region does have, on the other hand, is plenty of sun, so the roof of the structure would comprise of solar panels to power the heating and electricity needs of the resident population. The idea is to attract more residents to the area, which is one of the most sparsely populated regions in the world -- with only three people per square kilometre.