This grand building was the university's original observatory, founded in 1810. Its most famous director, F. G. W. Struve (in charge 1820 - 1839) installed what was then the most powerful telescope in the world. A shiny plaque in front honours Struve's Geodetic Arc, a string of survey triangulations stretching 2,820km from Norway to the Black Sea. The arc was put on UNESCO's Cultural Heritage List in 2005. The Observatory houses a museum that takes visitors through the observatory's history from the early-19th-century right up until the time of the Soviet space program. Here visitors can check out antique stargazing devices, try several interactive exhibits and climb outside for city views. Old-school planetary shows done on a mechanical projector will help you keep your zodiac signs straight.