The proposed ERC Advanced Grant “Strings&Gravity” is centered around string theory as a consistent theory of quantum gravity in the context of particle physics and cosmology. We are addressing several ground breaking and highly innovative questions about the structure of space and time and the nature of fundamental interactions at very short distances. In particular we are planning to investigate various new aspects concerning the fundamental relation between string theory and gravity. These contain the intriguing properties of string scattering amplitudes and its so far not understood relations to the new concept of classicalization as well as the relation between black hole production and the production of heavy string Regge excitations. This part of the project will be also relevant for the search of extra dimensions and for mini black holes at the LHC. Furthermore we are planning to investigate stringy background geometries, which generalize the concept of Riemannian manifolds. We are aiming to get new insights from string theory and from non-geometric string backgrounds into the problem of dark energy, which is one of the most mysterious parts of Einstein relativity in relation to Standard cosmology.This part of the project will be related to derive possible inflationary scenarios from new non-geometric compactifications without and with D-branes and background fluxes. The final aim of string theory will be to understand if the quantum structure of gravity and of space and time can emerge from an underlying and so far unknown dynamical principle, a problem which is equally important for the understanding of the Big Bang as for the physics of Black Holes.