Given a Riemannian manifold, it is a classical problem in analysis to establish pointwise bounds for eigenfunctions of the Laplace operator. Number theory enters the picture when the space admits some arithmetic structure such as a family of Hecke operators. In this talk, I will present methods from (mostly) number theory, Lie groups and automorphic forms to obtain "subconvex" bounds for sup-norms of Maass forms on GL(n) for arbitrary n (joint with P. Maga).