The Psychadelic Shop
According to Jessica Willamy, The Psychadelic Shop, also known locally as The Head Shop, was "the symbolic head" of the Haight, providing information and materiel necessary to take whatever recreational drug one desired. It was a particular proponent of LSD.
Located directly underneath the offices of the San Francisco Oracle, at the exact corner of Haight and Ashbury Streets in San Francisco, it was clearly a central experience to the lives of local residents. Ron and Jay Thelin, who also bankrolled the Oracle, opened it in 1966.
The Second Doctor, Ben and Polly visited the shop in January 1967, at which time the Doctor was particularly interested in various bongs and pipes that were on offer. (PROSE: Wonderland)
Behind the scenes
According to Peter Coyote's obituary for Ron Thelin, the Doctor's visit to The Head Shop must be viewed as a way in which the DWU is different from real life. The real Thelin closed the store on 6 October 1966 due to the criminalisation of LSD, and he gave away his entire inventory that evening. Thus the shop would not have been open for the Doctor to peruse in January 1967, when Wonderland is largely set.