There are two main buildings at this location: the visitor center, similar in design to a motel, and a Red Rocket station, which has a my stash box container. The office room of the visitor center has a wall safe that requires a Picklock skill of 2, as well as a cooking station, a first aid box, a tool case and pre-War money scattered on the floor.
Between the visitor center and the Red Rocket station is a honey beast sitting in the parking lot. It will typically attack both the player character and the nearby pack of feral ghouls, which can be led by a high-level glowing one. A steamer trunk can be looted on the balcony.
The Seneca Rocks Visitor Center appears only in Fallout 76.