Royal Observatory

There had been significant buildings on this land since the reign of Edward I. Greenwich Palace, next to the site of the present-day Observatory was the birthplace of Henry VIII and the Tudors used Greenwich Castle, which was built on the land that the Observatory now stands on. Greenwich Castle was apparently a favourite place for Henry VIII to house his mistresses, so that he could easily travel from the Palace to see them.

The establishment of a Royal Observatory was proposed in 1674 by Sir Jonas Moore who, in his role as Surveyor General at the Ordnance Office, persuaded King Charles II that the Observatory might be built with Flamsteed employed in it. The Ordnance Office was given responsibility for building the Observatory, with Moore providing the key instruments and equipment for the observatory at his own personal cost. Flamsteed House, the original part of the Observatory, was designed by Sir Christopher Wren probably with the assistance of Robert Hooke and was the first purpose-built scientific research facility in Britain. It was built for a cost of £520 (£20 over budget) out of largely recycled materials on the foundations of Duke Humphrey's Tower, which resulted in the alignment being 13 degrees away from true North, somewhat to Flamsteed's chagrin.

It not only housed the scientific instruments to be used by Flamsteed in his work on stellar tables, but over time also incorporated a number of additional responsibilities such as the keeping of time and later Her Majesty's Nautical Almanac Office.

Moore donated two clocks, built by Thomas Tompion, which were installed in the 20 foot high Octagon Room, the principal room of the building. They were of unusual design, each with a pendulum 13 feet (3.96 metres) in length mounted above the clock face, giving a period of four seconds and an accuracy, then unparalleled, of seven seconds per day.