The bar is a legend. Originally a blacksmith's shop, it later became a brothel and only became a bar during Prohibition, as a speakeasy. According to Castle, all the great writers drank there. Castle himself wrote most of his first book there, and only stopped going after his daughter, Alexis, was born.
After the events of "Last Call", it has also become a favorite hangout of Ryan, Esposito, Beckett and Castle after Castle bought it in order to save the bar from going under, with the captain joining them on at least one occasion. Ryan has discovered a route that gets them from the precinct to the bar in eight minutes.
In season 4 Cops & Robbers, it is mentioned that they still go regularly there.
In the season 6 Valkyrie, Beckett and Castle discover the thieves left the building through the sewers after remembering the secret entrance to The Old Haunt. When Beckett gets her job at the NYPD back, Castle announces that drinks at the Old Haunt that night will be on him.
- Brian Elliott, the Bar Tender: Got together with some investors and attempted to buy the bar, but was out-bid by Donny Hayes and remained on as bartender. He skims off the top by using a covert tracking system involving fruit, though he does this with, according to him, his boss's knowledge and tacit approval.
- Eddie, the Piano Man. Nearly two decades later, still recognizes Castle on sight and plays a few bars of his "action theme" when he sees him.
- Annie Swift, the waitress. A former target of Pickup Pete's unwanted affections.
- Ashes of Leo the Legend: The city's "best bartender since the days when 'gay' meant 'happy'". Also an amateur historian of the bar. When he died in 1997, his ashes were placed in an old silver shaker behind the bar.
- Pictures of great writers: a wall of famous patrons, including Hemingway, and (two over from him) Richard Castle.
- The Basement: A hidden basement, complete with Depression-era decor. It's accessed by pulling out and turning the electrical outlet. It was undisturbed for many years, but after the Flood of '98, Billy Pitt pulled up the linoleum and found it. Not merely cool, but awesome.
- The Basement (part 2): As if this isn't enough, the bookcase slides aside to reveal a secret-within-a-secret: a hidden passageway to the old sewer network, a secret storeroom, and the East River. The latter was built to accommodate notorious Mayor Jimmy Walker ("Beau James"), who was "famous for being a corrupt politician, renown womanizer and openly defiant of Prohibition". A shotgun boobytrap (now removed) is designed to deal with the unwary, and was the cause of the buckshot in Donny, when his body was found.
- The Basement (part 3): For decades, the hideaway kept its secret: a collection of 1875 St. Miriam Rock of Scotland. One bottle was used to kill Donny Hayes. Another was bought at auction for $26,000 by an internet millionaire, who mixed it with root beer. After the events of "Last Call", the scotch was claimed by the Mayor's office. One bottle is given to Castle, and one is seen in "Law and Murder" in the possession of the DA.
- Richard Castle: Bought the bar after solving Donny's murder. Unfortunately, the purchase did not include the rare scotch.
- Wilbur Pittorino : ("Billy Pitt"), an ex-con, owned the bar for many years. The bar was a drag financially, though, so he sold it to Donald Hayes for $150,000.
- Donald "Donny" Hayes : Donny had been practically raised in the Old Haunt by his grandfather, Leo the Legend, the only father Donny ever knew. Hayes bought the bar when Billy Pitt put it up for sale, out-bidding "TJ McChucklenuts" (a large corporate chain) and bartender Brian Elliot. Hayes was murdered in the secret stockroom by Steven Heisler, an upscale auctioneer who coveted Hayes's discovery of a cache of ancient and extremely valuable scotch in the basement.