During the period from 1662 to 1722, Ferdinand Verbient, a Belgian missionary, was put in charge of introducing European astronomical measurements and instrumentation in the Imperial Astronomical Bureau. Between 1669 and 1673, he supervised the construction of a celestial globe, an equatorial theodolite, a zodiac theodolite, an altazimuth, a quadrant, and an ancient sextant. Later another altazimuth and an armilla were built in 1715 and 1744 respectively.
In 1900, when the Allied Forces of Eight Powers invaded Beijing, everything was looted at the observatory. The French troops shipped the equatorial armilla, the ecliptic armilla, the azimuth theodolite, the quadrant and the abridged armilla to the French Embassy to China in Beijing. Two years later in 1902, under the pressure of public opinion, these astronomical instruments were returned to China. The Ming made armillary sphere, and Qing made armillary sphere, and Qing made celestial globe, armilla, azimuth theodolite, and the sextant were taken away by the Germans to Beriin. It was not until 1921 that these instruments were sent back to Beijing after World War I in compliance with the Versailles Peace Treaty.
After September 18, 1931 when the Japanese militarists launched a large-scale invasion to North China Plain, Chinese scientists shipped some of the instruments to Nanjing in 1932 for the sake of the cultural relics. Today they are displayed at Purple Hills Observatory and Nanjing Museum respectively.
Nowadays, on the platform of the Ancient Beijing Observatory as the visitor climbs it form right to left are displayed an armilla, a quadrant, a celestial globe, an ecliptic armilla, an altazimuth, an azimuth theodolite, a sextant and an equatorial armilla.
The brick terraced observatory consists of a 17-metre high platfrom. The top of the platform is 23.9 metres from west to east and 20.4 metres form south to north.