On Saturday, 25.03.2017 the 15. Astronomy Day will be held. An overview of activities can be found on the (german) Website of the Vereinigung der Sternenfreunde.
Of course, the Observatory in Aachen, (Sternwarte Aachen) opens it doors from 16h onwards. There will be activities for kids, as well as lectures and discussions for all ages. In addition, there will be a number of telescopes for observing the sun, stars or planets.
Food and drinks are available, entrance is of course free.
Some older images can be found on: http://www.fotowald.de/index-27.html