We prove that the boundary of a right-angled hyperbolic building is a universal Menger space. As a consequence, the 3-dimensional universal Menger space is the boundary of some Gromov-hyperbolic group.

We investigate Bruhat-Tits buildings and their compactifications by means of Berkovich analytic geometry over complete non-Archimedean fields. For every reductive group $\mathrm{G}$ over a suitable non-Archimedean field $k$ we define a map from the Bruhat-Tits building $ℬ(\mathrm{G},k)$ to the Berkovich analytic space ${\mathrm{G}}^{\mathrm{an}}$ associated with $\mathrm{G}$. Composing this map with the projection of ${\mathrm{G}}^{\mathrm{an}}$ to its flag varieties, we define a family of compactifications of $ℬ(\mathrm{G},k)$. This generalizes results by Berkovich in the case of split groups. Moreover,...