I've played cata tour guide for many people over the past couple of years and the one thing everyone wants to see are the bones.
The GRS (14th district) quarries have become synonymous with the storage with human remains. In reality the tunnels where bones are stored repersent only a tiny fraction of the network.
Today the network contains the remains of around 7 million people, most of which are located in the section officially open for public tours. There are still a few ossuaries (like the one above) in the network closed to the public but if you want to see the bones, I recommend you do the official tour. The simple reason for that is because the bones are in much better condition.
The rest of the network has been fairly well trashed, I have even noticed the level of the bones decreasing. When I first visited this room in late 2007, the level of the bones was at least 50cm higher. Who know where they have been going.