  The analogue of the Bruhat-Tits building of a p-adic group in F1-geometry is
a single apartment. In this setting, the trace formula gives rise to a several
variable zeta function analogously to the p-adic case. The analogy carries on
to the fact that the restriction to certain lines yield zeta functions which
are defined in geometrical terms. Also, the classical formula of Ihara has an
analogue in this setting.
