Summing over geometries in string theory

I discuss the question how string theory achieves a sum over bulk geometries with fixed asymptotic boundary conditions. I analyze this problem with the help of the tensionless string on AdS3xS3xT4 (with one unit of NS-NS flux) that was recently understood to be dual to the symmetric orbifold of T4. I argue that large stringy corrections around a fixed background can be interpreted as different semiclassical geometries, thus making a sum over semi-classical geometries superfluous.