The experimental support for general relativity up to the early 1990s is summarized in:
Theory and Experiment in Gravitational Physics, Revised Edition, C. M. Will (Cambridge University Press, Cambridge, 1993).
A more up-to-date treatment of the subject can be found in:
``The Confrontation between General Relativity and Experiment,'' C. M. Will, Living Reviews in Relativity 4, 4 (2001). Available online at http://www.livingreviews.org/lrr-2001-4