Green’s Dictionary of Slang

basing gallery n.

[basing n. + SE gallery, on the model of the heroin-users’ shooting gallery n. (1)]

(drugs) a place where crack cocaine users gather to consume their drug.

[US]T. Williams Crackhouse 4: By 1985, crackhouses – then called ‘basing galleries’ – were becoming the major institutions catering to cocaine users.