  Various theories beyond the Standard Model predict the existence of heavy
resonances decaying to Higgs (H) boson pairs. In order to maximize the
sensitivity of searches for such resonances, it is important that experimental
analyses cover a variety of decay modes. The decay of H boson pairs to four
$\tau$ leptons (HH$ \to \tau\tau\tau\tau$) has not been discussed in the
literature so far. This decay mode provides a small branching fraction, but
also comparatively low backgrounds. We present an algorithm for the
reconstruction of the mass of the H boson pair in events in which the H boson
pair decays via HH$ \to \tau\tau\tau\tau$ and the $\tau$ leptons subsequently
decay into electrons, muons, or hadrons. The algorithm achieves a resolution of
$7$-$22\%$ relative to the mass of the H boson pair, depending on the mass of
the resonance.
