Virgo Cluster.
The nearest rich cluster of galaxies at a distance of about 50-60 million light years and the centre of the Local Supercluster. It covers 120 square degrees of sky and contains several thousand galaxies. It is an irregular cluster with no central condensation. The giant elliptical galaxy M87 is the most massive in the cluster. A total of sixteen of the brighter members are included in the Messier Catalogue.