Moriarty's Saloon is one of the bars in the town of Megaton. Established in 2230, it is owned by a money-hungry man named Colin Moriarty. Drinks are served by the ghoul bartender Gob, and the saloon is also home to Nova, a prostitute who will sleep with the player (that is, next to them) if he/she rents a room for 120 caps.
This two-story scruffy metal housing with atrium is situated at the highest point of the whole Megaton crater.
The front door opens to the bar. The restroom is under the stairs, concealed by a drape.
The door behind the bar leads to the storage room containing Moriarty's terminal and the supply of the saloon. The backdoor in the storage room exits to behind the men's restroom.
On the second floor, there are four bedrooms. The first bedroom with a double bed is available for renting. The second room you cannot rent and has a bed, chair, and a filing cabinet. The third room in the corner is Moriarty's room with 2 chairs, a table with 2 beers and a squirrel stew on it and a bed with a Hard locked cabinet next to it and a metal box in the corner. The 4th and last room has just a bed and a filing cabinet.
Cabinet in the storage room has the password to Moriarty's terminal, though you can also get it from Nova with a speech challenge or the Lady Killer perk.
Moriarty is, according to Lucas Simms, privy to information about the Lone Wanderer's father, but also untrustworthy. Information can be gleaned through a bribe, successful use of Speech, hacking his computer, picking the lock on his filing cabinet, or outright killing the proprietor.
The cabinet in Moriarty's room (hard lock) can contain quite a few caps. Although Jericho claims that the key is "danglin' around Colin's neck," there is no key visible (since it was cut from the final version of the game), but can be picked.