## Harmonic maps into singular spaces

harmonic maps into singular spaces, in particular Euclidean buildings,

in order to understand p-adic superrigidity. The study was quickly

generalized in a number of directions by a number of authors. This

talk will focus on the work initiated by Korevaar and Schoen on

harmonic maps into metric spaces with curvature bounded above in the

sense of Alexandrov. I will describe the variational characterization