What are those structures at Taif Regional Airport in Saudi Arabia?
Those are hardened aircraft shelters, and each hangar is flanked by two blast walls (revetment). Those are for combat aircraft (the airport is mixed-use: public/military).

Since in that hemisphere the sun is to the south, the shadows tell us they are not sunken structures, i.e. the hangars and walls are higher than the taxiways.

The numerous taxiways are for redundancy against bombing. And the overall pattern makes it harder for a single bomb run to affect all hangars.

Here's an aerial close-up from another Saudi Arabian airport, Tabuk Regional Airport:


  
  Source: flickr.com