A stringy glimpse into the black hole horizon

We elaborate on the recent claim [1] that non-perturbative effects in α′, which are at the core of the FZZ duality, render the region just behind the horizon of the SL(2, ℝ)k/U(1) black hole singular already at the classical level (gs = 0). We argue that the 2D classical SL(2, ℝ)k/U(1) black hole could shed some light on quantum black holes in higher dimensions including large black holes in AdS5 × S5.