The Rogues' Den is found under Burthorpe's Inn. He is walking around a fire that never goes out, which is why this is a great spot for training the Cooking skill. You can bank very quickly and you will be cooking on the everlasting fire. You can train extremely fast when you bank as he comes near the fire. Some players even train Fletching or Firemaking here, also for the fast banking. You can also train Thieving here at 4 spots where it is possible to obtain gems and coins. Emerald Benedict is close to these spots, so it's also a good spot for obtaining gems.