Kourindou (Kōrindō, lit. Hall of Fragrant Rain, 香霖堂) is an antique store seated between human civilization and the Forest of Magic, run by Rinnosuke Morichika.
Though it's a somewhat well-known establishment for folks in the world of Touhou, Rinnosuke rarely (if ever) actually sells anything, despite keeping an exhaustive inventory - he mostly trades and/or puts up with "creative borrowing."
On occasion, the store is used for completely non-business ventures, such as cooking and combat. The store has also taken quite a bit of damage over time, thanks to conflicts that involve the store's occupants.
The inventory of Kourindou is (presumably) its main draw, as it mostly includes items from the outside world. Teacups, feather pillows, computing magazines, kerosene heaters, and even an iPod have made their way there over time.
As Kourindou only appears in a side story (Curiosities of Lotus Asia follows a somewhat different timeline than the games), no character in a game has actually visited Kourindou yet (as of Subterranean Animism), though Marisa has mentioned it to Reimu in the Match Mode of Phantasmagoria of Flower View. Also, in Sanae B's scenario in UFO, Nazrin mentions a shop which may be Kourindou.