Following major seismic events occurred in Italy over the last 50 years, a notable amount of data relevant to post-earthquake damage of ordinary buildings was collected. These data today represent an inestimable scientific heritage, useful for prevision and prevention purposes, including calibration of vulnerability models for seismic risk assessment and formulation of damage scenarios. However, the data sets resulting from different inspection tools developed over the years are not immediately comparable with each other. The need for enhancing the reliability of prevention models and more effectively support strategic decision-making has moved the Italian Civil Protection Department to undertake, since 2014, a specific project with this ambitious goal. Developed with the technological support of Eucentre Foundation, the web-gis platform, named Da.D.O. (Observed Damage Database), is meant to store and to share data from large post-earthquake damage campaigns occurred in the past. Da.D.O. is addressed to Civil Protection Department users, members of the scientific community and Regions, though its access could be further extended in the future to other stakeholders. The paper describes goals, contents and capabilities of the IT platform, which, at present, includes data sets relevant to nine seismic events (or sequences) occurred from 1976 (Friuli earthquake) to 2012 (Emilia-Romagna earthquake).