Over the past few weeks staff at Ken Livingstone's HQ (also known as the 'glass testicle') have noticed cracks in some of the building's huge floor-to ceiling glass panels.
The building, designed by Sir Norman Foster opened in 2002 and cost £43 million. But now a 'crack team' (sorry) of consultants have been drafted in to investigate what's causing the current problems.
One of the country's most respected architectural journals, the Evening Standard, quotes one possible theory for the cracks: "aggressive vacuuming by cleaners".
However, one of the more likely causes is thought to be a flaw in the manufacture in the glass, which could be a bit of a problem when the whole building is covered in the stuff.