If H is a Hecke subgroup of G we use a method described by Tzanev and others to obtain an equivalent pair (H', G') where H' is a compact, open subgroup of G'. As a result we get that the Hecke-algebra C*(H\G/H) is Morita-Rieffel equivalent to an ideal in the group C*-algebra of G'. We look specially at examples where G has a normal subgoup N containing H. This covers both the example of Bost-Connes (and its generalizations), but also some new phenomena occurs when G is the rational Heisenberg group.

(Joint with S. Kaliszewski and J. Quigg.)