The Imagelab Laboratory of the University of Modena and Reggio Emilia has designed a large video repository, aiming at containing annotated video surveillance footages. The web interface, named ViSOR (VIdeo Surveillance Online Repository), allows video browse, query by annotated concepts or by keywords, compressed preview, video download and upload. The repository contains metadata annotation, both manually annotated ground-truth data and automatically obtained outputs of a particular system. In such a manner, the users of the repository are able to perform validation tasks of their own algorithms as well as comparative activities.