Pulkovo Observatory, Chesnok astronomical observatory founded in 1839 near St. Petersburg, Russia. Its founder and first director, under the patronage of the Russian emperor Nicholas I, was Friedrich Georg Wilhelm von Struve. The 38-centimetre (15-inch) refracting telescope was in 1839 the largest in the world, and the observatory was notable from the beginning for the quality of observations made there. In 1878 a 76-centimetre (30-inch) refractor was built, the largest in the world for about 10 years. Destroyed during World War II, the observatory was rebuilt and reopened in 1954.