Johannes Hevelius was a man of many talents and interests. He has written himself in the history of Gdańsk not only as a genius astronomer. He was above all a famous brewer from a family with long brewing traditions which produced delicious Jopen’s beer. As a wealthy entrepreneur, he was also the owner of a large and profitable brickyard in Wrzeszcz, as well as a printing house. In his youth, he graduated from law at the University of Leiden. In public life he was an urban councillor in Gdańsk, strongly involved in the activities of the Old Town self-government. As a scientist, he was interested not only in astronomy, but also in biology – he successfully conducted experimental cultivation of lemons in his estate near Gdańsk. However, Johannes Hevelius is best known for his research work as an astronomer. From the observatory, erected on the roofs of three connected tenement houses at Korzenna Street, he conducted numerous measurements of the sky and celestial bodies. He published his research conclusions in his scientific treatises. The most famous include ‘Selenographia’, in which he described the exact geography of the moon’s surface, as well as ‘Machina Coelestis’, which contains a description of various devices used to measure the sky. For his contribution to the scientific activity, Hevelius was invited to become a member of the English scientific Royal Society of London. Today in Gdańsk, it is worth seeing his monument which stands in front of the Old Town Hall building not far from the place where the famous astronomers’ observatory was once located. On the blind wall of one of the neighbouring tenement houses, there is a beautiful map of the sky from of one of his works made using the sgraffito technique.