Abstract: Since the seminal work of Atick and Witten in '88, it has been clear that the thermal compactification of a Type II string behaves, in the high-temperature limit, like a Type 0 string. At finite temperatures, the exact T-duality involves a peculiar compactification of the Type 0 string where the tachyon is antiperiodic. In this talk, I will discuss some ongoing work motivated by this duality. After reviewing the duality, I will discuss the worldsheet realization of more general compactifications of Type 0 strings involving this Z2 symmetry. We will see that, surprisingly, they actually require Type II string perturbation theory. Time permitting, I will then get to an exotic T4/Z2 orbifold in which, at the fixed points, the tachyon vanishes and massless fermions arise.