Open star clusters are representatives of the young stellar population in the Galactic disk. They are directly related to the locations of star formation. In the past decade we determined the astrophysical parameters of some 3000 open clusters in the solar neighborhood, based on membership determination from ground-based astrometry and photometry. This sample is, in general, complete up to a distance of 1.8 kpc from the Sun. However, for the oldest clusters - ages above 1 Gyr - we find an underdensity within 1 kpc from the Sun. The highly improved astrometric accuracy of the Gaia data releases enables new possibilities to detect those clusters. I will report on early successes, as well as on work in progress.