So yea ive found this out the other day and pretty much got it all down. to find this location, when you start off on the free explore, just go left and keep going through all teh tunnels and such and youll eventually make it to Skywatch. enjoy the grind my friends.
Edited: 7/24/2014 12:35:10 AM PermalinkHahah thanks for this dude I'm going to try that area ASAP. Those Fallen spawning in that cave and increasing in power and then the Servitors appearing is insane! Even though it's low level I found a similar technique where you first spawn from leaving the Tower. The few caves and buildings on the right spawn chests of different kinds quite often.