We develop the structure theory of full isometry groups of locally compact non-positively curved metric spaces. Amongst the discussed themes are de Rham decompositions, normal subgroup structure, and characterizing properties of symmetric spaces and Bruhat-Tits buildings. Applications to discrete groups and further developments on non-positively curved lattices are discussed in a companion paper [27].
Caprace, P.-E., & Monod, N. (2009). Isometry groups of non-positively curved spaces: structure theory. Journal of Topology, 2(4), 661-700. https://doi.org/10.1112/jtopol/jtp026 (Original work published 2009)