Mounting Ceiling Fan to Old Junction Box
Boxes mounted with a center nut/collar are usually installed between joists on a support bar like the picture below. You're going to have to cut away the ceiling to expose the entire box. The cloth wiring you have is very old and there's a good chance it will crumble and the insulation will crack when you move it around. You'll have to straighten out the wire carefully, after you've turned off the breaker supplying the circuit. Then remove the nut/ threaded collar from the threaded nipple. The box should come loose. Remove any clamps holding the wires in place and unconnect any wires to completely remove the box. Take pictures so you'll know how to reconnect them. You might have to cut away a bit more of the ceiling to get behind the box to undo the clamps. Cut away the box support and install another one similar to the one below but rated for a ceiling fan. Run the wires into the new box and then attach the new box to the support bar. Repair ceiling or get a fan cover plate. Mount your new fan. 

This will be very risky for a DIYer because the wire is so very old and likely to be unusable after moving it around so much. In that case, you'd have no option but to rewire the entire circuit. Being in a condo, there are probably rules about homeowners doing electrical work in their units. Consulting a pro might not be a bad idea.