Pulkovo (pōlˈkəvə) [key], astronomical observatory, S of St. Petersburg, NW Russia. Pulkovo was built (1834–39) under a commission headed by F. G. W. von Struve. In 1839 its 15-in. (38-cm) refracting telescope was the largest in the world. A leading observatory during the 19th cent., it added a 30-in. (76-cm) refractor in 1878. After the Bolshevik Revolution (1917), Pulkovo became a major astronomical observatory of the Soviet Academy of Sciences. It was rebuilt (1946–54) after suffering severe damage in World War II. The observatory designed and tested what was the world's largest reflecting telescope, 236 in. (6 m) in diameter, now located in Zelenchukskaya, the Caucasus.