Some boron-doped germanium clusters B x Ge 12 q with x = 1, 2, 3, and 4 and q = 0, 1 were designed as stabilized double ring tubes. While the B 2 Ge 12 constitutes the smallest deltahedral germanium cluster, both B 3 Ge 12 + and B 4 Ge 12 clusters present us, for the first time, with an endohedral tubular motif in which either the B 3 or the B 4 cycle is encapsulated inside a Ge 12 hexagonal prism tube. Both B 3 and B 4 units thus satisfy a geometry requirement to create an endohedral structure within the Ge 12 double ring. Keeping their high symmetry, both B 3 and B 4 units generate delocalized bonds upon interaction with the Ge 12 tubular framework and thereby induce an aromatic character for the resulting B 3 Ge 12 + and B 4 Ge 12 , respectively. Their aromaticity was probed by the magnetic responses of electron densities. Such a tubular aromaticity appears to greatly contribute to the high thermodynamic stability of the binary hexagonal germanium tubes.