The only fortress variant that contains a detector tower within. It's not necessary to destroy the detector tower for the game to consider the fortress destroyed.
Visually- Detector Tower
On the map- Oblong perimeter - same as Crane and Bunker Hell. 4 large radar signatures lined up on one side
Strategy possible as of Patch 1.001.102
https://www.youtube.com/watch?v=utFI940QQrQ
I throw the Orbital Laser to destroy 3 of the fabs and then eruptor one more for extra reliability (the laser can get distracted by hulks or dropships). I commando the last two and GTFO. The most speedrun viable clear in the new patch.
https://youtu.be/e31pRbrY40o?t=725
this is an example of a non speedrunners solo clear.
There is a unique and ominous banner post filled with skulls in the lower part of the base
Also, of course one does not simply walk into Mordor:
https://youtu.be/b2t_qDqpij8?t=97
Zovc for map and Clark for annotations