30 years of multi-wavelength observations of 3C 273

We present a wide multi-wavelength database of most observations of the qua sar 3C 273 obtained during the last 30 years. This database is the most com plete set of observations available for an active galactic nucleus (AGN). I t contains nearly 20 000 observations grouped together into 70 light curves covering 16 orders of magnitude in frequency from the radio to the gamma-r ay domain. The database is constituted of many previously unpublished observations and of most publicly available data gathered in the literature and on the Worl d Wide Web (WWW). It is complete to the best of our knowledge, except in th e optical (UBV) domain where we chose not to add all observations from the literature. In addition to the photometric data, we present the spectra of 3C 273 obtained by the International Ultraviolet Explorer (IUE) satellite. In the X-ray domain, we used the spectral fit parameters from the literatur e to construct the light curves. Apart from describing the data, we show the most representative light curve s and the average spectrum of 3C 273. The database is available on the WWW in a homogeneous and clear form and we wish to update it regularly by addin g new observations.