Astronomical observatory "Nicolaus Copernicus" is the first astronomical complex in Bulgaria which was officially opened on 22nd May 1968 in Varna and it consisted of an observatory, a planetarium and a tower with a Foucault pendulum. There are 80 seats in the sky theatre. The planetarium is model ZKP-1. The diameter of the dome is 10 meters. A projector that shows the Solar System and a video projector with a computer and a sound system are installed, too. The Foucault pendulum is installed in a special tower. This is the only one Foucault pendulum on the Balkan Peninsula.