Abstract
If one of the main purposes of Astrometry is the determination of celestial positions and motions, the construotion of an inertial referenoe frame must be a fundamental aspect of these purposes. The problems for the construotion of an inertial reference frame and their solutions, now in progress using modern techniques, are briefly reviewed - The contributions made in this context to Fundamental Astronomy at Cerro Calan Observatory, Santiago, using extrameridian astrometrical methods, are described.
