Triangular hyperbolic buildings
  We construct triangular hyperbolic polyhedra whose links are generalized 4-gons. The universal cover of those polyhedra are hyperbolic buildings, which appartments are hyperbolic planes tesselated by regular triangles with angles $\pi/4$. Moreover, the fundamental groups of the polyhedra acts simply transitively on vertices of the buildings. 
Riikka Kangaslampi, Alina Vdovina