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Hipparcos, the first ever experiment of global astrometry, was launched byESA in 1989 and its results published in 1997 (Perryman et al., Astron.Astrophys. 323, L49, 1997; Perryman & ESA (eds), The Hipparcos and Tychocatalogues, ESA SP-1200, 1997). A new reduction was later performed using animproved satellite attitude reconstruction leading to an improved accuracy forstars brighter than 9th magnitude (van Leeuwen & Fantino, Astron. Astrophys.439, 791, 2005; van Leeuwen, Astron. Astrophys. 474, 653, 2007).  The Hipparcos Catalogue provided an extended dataset of very accurateastrometric data (positions, trigonometric parallaxes and proper motions),enlarging by two orders of magnitude the quantity and quality of distancedeterminations and luminosity calibrations. The availability of more than 20000stars with a trigonometric parallax known to better than 10% opened the way toa drastic revision of our 3-D knowledge of the solar neighbourhood and to arenewal of the calibration of many distance indicators and age estimations. Theprospects opened by Gaia, the next ESA cornerstone, planned for launch in June2013 (Perryman et al., Astron. Astrophys. 369, 339, 2001), are still much moredramatic: a billion objects with systematic and quasi simultaneous astrometric,spectrophotometric and spectroscopic observations, about 150 million stars withexpected distances to better than 10%, all over the Galaxy. All stellardistance indicators, in very large numbers, will be directly measured,providing a direct calibration of their luminosity and making possible detailedstudies of the impacts of various effects linked to chemical elementabundances, age or cluster membership. With the help of simulations of the dataexpected from Gaia, obtained from the mission simulator developed by DPAC, wewill illustrate what Gaia can provide with some selected examples.

Building the cosmic distance scale: from Hipparcos to Gaia