It was during his stay in Prague that Einstein started in earnest to develop his ideas about general relativity. I will recall those days in 1911 and 1912, discuss Einstein's papers on gravitation from that period and emphasize which new concepts and ideas he introduced.
I alsowant to indicate howthe main themes that preoccupied him then, the principle of equivalence, bending of light, gravitational redshift and frame dragging effects, are alive in contemporary relativity.