We discuss the notion of translation-invariant vacua for 2d chiral algebras
and relate it to the notion of the associated variety. The two-dimensional
chiral algebra associated to four-dimensional ${\cal N}=4$ $U(N)$ SYM has a
conjectural holographic dual involving the B-model topological string theory.
We study the effect of non-zero vacuum expectation values on the chiral algebra
correlation functions and derive a holographic dual Calabi-Yau geometry. We
test our proposal by a large $N$ analysis of correlation functions of
determinant operators, whose saddles can be matched with semi-classical
configurations of "Giant Graviton" D-branes in the bulk