Sonnenborgh Observatory is an astronomical observatory and museum open to the public, located in Utrecht, Netherlands. It is located in one of the four stone forts built by Charles V as defense buildings for Utrecht. In 1639 the fort was expanded with an academic herbal garden by members of Utrecht University, three years after its founding. The garden was moved in 1724 to the current location of the Oude Hortus. During reconstruction works in 2001 remains were found of the first chemical laboratory in Utrecht, third in the world. The lab was led by the first chemistry-only professor in Utrecht Johann Conrad Barchusen.