Step Into Wonder

Walk beneath the Great Refractor. Wander historic halls. Gather under the night sky. Every visit to Yerkes is a chance to see the universe—and yourself—a little differently.

Know Before You Go

Plan ahead to make the most of your visit. Here are a few key things to know before you arrive, from ticketing and access to helpful resources.

Interior access is available by advance ticket only during scheduled tours and events, with tickets released 2 months in advance.

The arboretum and outdoor trails are open sunrise to sunset and do not require a ticket. Grounds are typically open, but may occasionally close for private events.

If you have questions, please call 262-245-5555 (our phones are answered M-F from 9-3) or fill out the contact form.

For details about accessibility, parking, or weather considerations, please see our FAQs.

Tours & Events

Plan Your Adventure

These are the experiences that define Yerkes: immersive, intimate, and unlike anywhere else.

1 Hr 30 min

All Ages

Stairs

Frostlights

Yerkes transforms into a winter galaxy of light and sound inside the architectural masterpiece dome housing the world’s largest lens telescope.

1 Hr 30 Min

Ages 5+

Partially Accessible

Space & Spaces Tour

Stand beneath the world’s largest refracting telescope. Explore sweeping architecture and the human stories that shaped modern astronomy.

1 Hr 45 Min

Ages 14+

Partially accessible

Director’s Hidden Spaces

Wind through staircases, corridors, and tucked-away rooms rarely open to the public. A behind-the-scenes look at the observatory few get to see.

2 Hours

Ages 13+

Stairs

SOLD OUT – Exploring the Night Sky

This tour is sold out for 2026. When skies are clear, view the cosmos through the Great Refractor and experience astronomy as it was meant to be.

2 Hours

Ages 13+

Stairs

SOLD OUT – Exploring the Night Sky with the 24″ Reflector

This tour is sold out for 2026. This immersive 2-hour experience illuminates the inner-workings of Yerkes after dark.

Help Discovery Thrive

Your generosity helps keep Yerkes open, accessible, and alive with curiosity by fueling programs, preserving a historic landmark, and inspiring generations to come.