Built in the summer of 1877 by young Englishman John H. Tunstall and his partners, Alexander McSween and John Chisum, this building originally housed a store, Alexander McSween’s law office, the offices of the Bank of Lincoln, and living quarters for John Tunstall. The land on which it was built had been purchased from L. G. Murphy by Alexander McSween in February 1877. After John Tunstall’s murder, his friends used the corral wall located at the east end of the building to ambush and kill Sheriff William Brady and Deputy George Hindman.

Though it played a central role in starting the Lincoln County War, it was largely unoccupied during the Five-Day Battle. After Tunstall’s death, the building passed through a series of owners that included Susan McSween, Joseph A. Larue, James J. Dolan, and William Rosenthal & Company. Eventually, the Tunstall Store was connected to another, a previously separate building to the west, and a pitched roof was added that tied the buildings together. In 1901, the store was owned by the Roswell Trading Company and operated by their manager, John M. Penfield. Penfield bought out the previous owners in 1914, and he and the Penfield family carried on the business until 1957, when the property was conveyed to the State of New Mexico and turned into a public museum.