This paper describes the RF measurement storage and database architecture for long-term continuously running spectrum observatories in the US (at Chicago and Blacksburg) and in Turku, Finland. It also describes how the measurement band plan has been collaboratively created taking into account the specifications and limits of the receiving system. Collecting measurements from different geographical locations makes it possible to perform spatial and temporal analysis of the spectrum usage in different parts of the world. As the multi-site measurements are aggregated into one central database, very high requirements are set on the database architecture, equipment, capacity, speed and number of data connections.