  We describe solutions of asymptotically AdS$_3$ Einstein gravity that are
sourced by the insertion of operators in the boundary CFT$_2$, whose dimension
scales with the central charge of the theory. Previously, we found that the
geometry corresponding to a black hole two-point function is simply related to
an infinite covering of the Euclidean BTZ black hole. However, here we find
that the geometry sourced by the presence of a third black hole operator turns
out to be a Euclidean wormhole with two asymptotic boundaries. We construct
this new geometry as a quotient of empty AdS$_3$ realized by domes and doors.
The doors give access to the infinite covers that are needed to describe the
insertion of the operators, while the domes describe the fundamental domains of
the quotient on each cover. In particular, despite the standard fact that the
Fefferman-Graham expansion is single-sided, the extended bulk geometry contains
a wormhole that connects two asymptotic boundaries. We observe that the
two-sided wormhole can be made single-sided by cutting off the wormhole and
gluing on a "Lorentzian cap". In this way, the geometry gives the holographic
description of a three-point function, up to phases. By rewriting the metric in
terms of a Liouville field, we compute the on-shell action and find that the
result matches with the Heavy-Heavy-Heavy three-point function predicted by the
modular bootstrap. Finally, we describe the geometric transition between doors
and defects, that is, when one or more dual operators describe a conical defect
insertion, rather than a black hole insertion.
