Sonnenborgh

Current exhibitions

About the museum

Sonnenborgh brings together two eras. The bastion was built in the mid-16th century on the orders of Emperor Charles V, who had Utrecht fortified with four bastions against the new artillery; Sonnenborgh is the only one of them to survive almost intact. In the 17th century the university laid out its first botanical garden here, and around 1700 the chemist Johann Conrad Barchusen set up one of the earliest chemical laboratories in the casemates.

In the mid-19th century, the new university observatory was built on the bastion; King Willem III laid the foundation stone in 1853. The core building was designed by the physicist Buys Ballot, who also founded the meteorological institute KNMI here in 1854 – it did not move to De Bilt until 1897. Around 1930, the solar research of Marcel Minnaert and Kees de Jager made the observatory internationally known.

After the astronomical institute moved out in 1987, Sonnenborgh became a museum and public observatory. Between 1998 and 2003, archaeologists uncovered the buried bastion again. In 2018 the renewed exhibition "Ver weg komt dichterbij" opened, and in 2020 the site was recognized as national chemical heritage.

Today the museum presents astronomy and meteorology in largely original rooms: the meridian hall, the solar laboratory, and domes with the 1863 Merz refractor and a large solar telescope. Stargazing evenings are held during the winter half of the year.

Highlights

• 1863 Merz refractor in a rotating dome
• Largest solar telescope in the Netherlands (views of the sun on Sundays)
• Meridian hall and solar spectrograph from Minnaert's time
• Bastion from 1552 with remains of an early chemistry lab
• Stargazing evenings from October to March

Permanent exhibitions

• Ver weg komt dichterbij – Interactive astronomy exhibition with a tablet guide through the observatory and bastion – from solar research and timekeeping to black holes.
• Op Aarde – Immersive exhibition with art and science installations about climate and our relationship with the Earth; suitable for ages 16 and up.

Operated by

Stichting Museum Sterrenwacht Sonnenborgh

Director

Giovanni Stijnen

Visitors per year

approx. 34,774 (2025)

Admission & discounts

Free with the Museumkaart (not sold on site); also free with the VriendenLoterij VIP-KAART (cardholder only), NVON membership card and Voedselbank Cultuurpas. U-pas: adults €8.50, children €5.50. Museum tickets only on the day of the visit at the ticket desk, card payment only. Prices as of January 1, 2026.

Accessibility

• Partially wheelchair accessible
• Elevator: not available
• Accessible restroom: not available
• Accessible parking
• Service dogs welcome
• Tactile models & exhibits
• Sign language tours: no information
• Easy-to-read materials: no information
• Audio description: no information

Listed historic buildings with thresholds and heavy doors, no elevators; telescopes and bastion reachable only by stairs, no wheelchair-accessible restrooms. Accompaniment recommended. Public accessible parking spaces at Lange Nieuwstraat 106 and Servaasbolwerk 2-3. Every two months on a Sunday (or by arrangement), "Sterren kijken met handen en oren" tours for visually impaired adults; handrails and tactile markings. Quieter days: Tue–Thu.

Kids & families

Great for kids & families

• Family tours & workshops
• Activity booklet, scavenger hunt or kids’ audio guide
• Hands-on stations

The permanent exhibition is designed for children aged 8 and up; for ages 3–6 there is the "Voetzoekertjes" search game. Children's observation evenings on Saturdays (ages 6–12, October–March), "Kosmische kindercolleges" (cosmic lectures for kids) for ages 8–12 on the last Wednesday of the month, youth astronomy courses. The "Op Aarde" exhibition is suitable only for ages 16 and up.

Getting there & parking

Entrance on the edge of the Zocherplantsoen in the white building at the top of the hill.

Amenities & dining

• Café: not available
• Restaurant: not available
• Museum shop
• Wi-Fi

No café or restaurant; food brought along may be eaten in the garden. Museum shop (including eclipse glasses) also accessible without a ticket.

Events & venue rental

• Spaces for rent
• Private parties
• Corporate events
• Weddings / ceremonies

Terreplein (with glass roof), library, Collegezaal (lecture hall) and garden via the caterer Qeet (info@qeet.nl, +31 30 696 6121) for parties, weddings, conferences and dinners.

Plan your visit