"Shapolsky et al. Manhattan Real Estate Holdings, a Real-Time Social System, as of May 1, 1971 documents the ownership and control of urban space. The work exposes the properties and transactions of Shapolsky et al. Manhattan Real Estate Holdings, which in 1971 represented the biggest concentration of real estate in New York under one group, and it is still an active corporation today. The properties of the group were found primarily in the Lower East Side and Harlem, two neighbourhoods characterised by their ethnic and racial minorities. The information was culled from New York City public records and covered approximately twenty years prior to 1971. About seventy companies proved to be the owners of these properties, often interchanging among each other mortgages or properties, which obscured ownership and granted fiscal advantages."