Two of the rare police hats can be found here. One is in an office near a cash register, and another is in the center of the room perched above the toilet on a piece of concrete jutting out from a supporting column. Standing on the empty deathclaw cage enables access to the latter one.
Two mini nukes, sitting on a ledge inside of the fallen length of radio tower in the center of the area. To retrieve them, you can either shoot them off the ledge and then gather them from the floor below; or make your way up to the east side of the highest level of the building and jump into the length of tower's open end.
One Nuka-grenade hidden underneath a desk. Go up the wall as high as the pile of debris will go, turn right and walk along the wall to find the desk.
It is possible to get to the upper levels, try climbing the rubble that is immediately to the left as you enter the open zone. An inquisitive player is rewarded by finding small amounts of more exotic ammunition and some chems on the upper floors, such as a Nuka-grenade, electron charge packs in buckets, as well as access to ammunition boxes and Nuka-Cola vending machine.
The S. Wilson Building doesn't match any surface building in Old Olney, being five stories tall with billboards and a collapsed radio tower on the roof, features no building visible in Old Olney has.
An Enclave Vertibird is on the highest level, inaccessible to the player. If fired upon, it will catch on fire and then attempt to flee shortly before exploding.
The level just below the Vertibird is inaccessible. Accessing it on the PC version via console commands reveals that there are missing walls and no loot (except for the randomly-generated contents of a few desks and/or filing cabinets).
Via console commands, one can find a gnome holding an iron next to an ironing board with a teddy bear on it. Disabling clipping allows a player to go through the wall beyond the stairs which exit into the Powerworks, to find the otherwise inaccessible gnome.