Sonnenborgh Museum en Sterrenwacht (Sonnenborgh Museum and Observatory), Utrecht

Perched atop the only surviving bastion of Utrecht’s 16th-century city walls, the Sonnenborgh Museum and Observatory is a unique blend of scientific exploration and historical depth. Originally built in the mid-1500s under the orders of Emperor Charles V, the bastion was designed to fortify the city against the latest military threat of the time: mobile cannons. The structure, with its meter-thick walls still bearing cannon holes, remains a testament to Utrecht’s military past.

By the 17th century, Sonnenborgh took on a more academic role when Utrecht University established its first botanical garden on the site in 1639. Over a century later, in 1724, the garden was relocated to what is now the Oude Hortus. Archaeological discoveries in the late 20th century further unveiled Sonnenborgh’s scientific heritage, revealing the remains of Utrecht’s first chemistry laboratory-one of the oldest in the world-led by Johann Conrad Barchusen.

Sonnenborgh became Utrecht University’s observatory in 1853 and housed the Royal Dutch Meteorological Institute (KNMI) from 1854 to 1897. It contributed to pioneering solar research, aiding the creation of one of the first solar atlases. Until the early 20th century, it also helped determine Utrecht’s official time with its Meridian viewer.

Today, Sonnenborgh is a public observatory and museum where visitors can engage with astronomy, meteorology, and the bastion’s rich history. Through interactive exhibits, guests can observe the sun using a specialized solar telescope, predict the weather like a 19th-century meteorologist, or explore the stars and planets through historic telescopes. The museum’s innovative approach includes a guided tablet tour that encourages hands-on experiments, making science accessible for all ages.