The Trinity Building has 9 rooms, with many scribbles on the walls. It has two pieces of un-effective cover outside. It is possible to climb to the roof of the building.
The Trinity Building has civillian-grade weaponry and essentials. It is not a very popular location for it's loot. It should only be looted if you are looking for a low-difficulty area with a low-level loot payoff.
It also has a fair share of Military loot, mostly the M9 and the MP5.