For 3 1/2years, where the 144,000 will hide during the Great Tribulation. "The 144,000" Rev 7

Where 144,000 will hide during the Great Tribulation. "The 144,000" Rev 7
PETRA, JORDAN.
This is in DESERT conditions! The carved out hillsides are 7 MILES LONG! Who did this and why? What tools were used? Where did their food come from? WHY DID THEY DO IT? How many people did it take to make this? Did they have a hospital if anyone got hurt?