Observatory Sonnenborgh is located on a beautiful, high spot on the Utrecht canal. It is a place with a special history that dates back to the year 1122. In that year, Utrecht received city rights and was allowed to build a city wall surrounded by a city moat.
Once in a while the city wall, of which nothing remains today by the way, was adapted to the ever-changing way of waging war. A major adaptation took place in the sixteenth century, commissioned by Emperor Charles V. Four bastions were built to house large cannons. Sonnenborgh was the second bastion completed. Enemies trying to cross the canal by boat or raft could be fired upon from the side of the bastion. Due to the pentagonal shape of the bastion, the own cannons were well protected from enemy cannonballs.
I n the seventeenth century, the bastions fell into disrepair. Sonnenborgh was converted into a hortus botanicus et medicus: a botanical garden where the newly founded Utrecht University conducted research, including research into medicine. But the high altitude proved to be unsuitable for a botanical garden, and so the garden soon moved elsewhere in the city. A chemical laboratory was then set up in Sonnenborgh - the very first in the world.
In 1851, the observatory moved into the building. The old observatory's location, the Smeetoren, was in fact demolished along with the rest of the city wall. Three years later, the Royal Dutch Meteorological Institute (KNMI), a scientific organization for meteorology, joined the observatory here. In 1879, KNMI moved to De Bilt, but the observatory remained. With the three telescopes Merz, Gala and Lunt, you can get close to the universe and view the planets, moon and sun on clear nights. Besides being an observatory, Sonnenborgh is also a museum of weather and astronomy. There, you can learn all about the universe, and of course about the bastion itself. Even the rings that once held the cannons can still be seen!