In his 1985 paper "The field of reals with a predicate for powers of two" Lou van den Dries studied the expansion of the real field by a predicate for a cyclic multiplicative subgroup of the reals. He axiomatized its theory and showed that it has quantifier elimination. This result had a significant influence on work by myself and others. I will review some of this work, in particular on expansions of the real field by multiplicative subgroups, and will mention recent joint work with Erik Walsberg.