For 80 years, Pentagon was the world's largest office building. But that title has now been taken by a building in Gujarat's Surat that will house a diamond trading centre, according to a CNN report. Surat is known as the gem capital of the world where 90 per cent of the world's diamonds are cut. The newly-constructed Surat Diamond Bourse will be a "one-stop destination" for over 65,000 diamond professionals, including cutters, polishers and traders, the outlet further said.