General relativity: basic ideas and observables

This stet of lectures will review the basic ideas and techniques of the present "standard" description of gravity (i.e. general relativity). A few examples of the applications of general relativity to the description of the macroscopic world will be given (solar system, gravitational waves, black holes, cosmology). We shall then address the following questions: 1) Which elements of general relativity have been really tested so far? 2) What types of new, macroscopically coupled fields could contribute to "gravity", and yet have escaped detection so far?