  We propose a new haloscope geometry that can arbitrarily increase the
resonator volume for a given target axion mass. This geometry consists of
closely packed, overlapping coaxial cavities operating as a single resonator.
While the resonant frequency is still determined by the dimensions of the
individual "cells," the strong interactions between the cells encourage the
entire "beehive" to oscillate in phase, a phenomenon expected of tightly
coupled harmonic oscillators. This synchronization behavior allows the
construction of a singly connected large-volume resonator at high frequency by
simply increasing the number of the cells. Using direct numerical simulations,
we verify the existence of a global eigenmode that has a high (40%) form factor
in a 169-element beehive resonator. The resonant frequency of the eigenmode is
tunable by moving the center rods laterally in unison. The form factor is very
tolerant to dimensional deviations and misalignment, as a result of mode
hybridization due to strong coupling. The beehive haloscope inherits many
appealing properties from the conventional coaxial cavity: a high quality
factor, compatibility with a solenoid magnet, ease of fabrication, tuning, and
coupling. We argue that this geometry is an excellent candidate for high-mass
axion searches covering the post-inflationary parameter space (>5 GHz).
