Due to a staffing shortage, beginning July 21, 2022, all tours of the HCO Plate Stacks, in addition to tours of the Great Refractor led by the Head Librarian, are suspended. We hope to resume tours soon. 


All visitors must abide by Wolbach Library's Code of Conduct and follow the Library's policy on Events and Tours while at the Observatory. The following restrictions are particularly relevant to tours:

  • No food or drinks 
  • No touching objects unless something is directly handed to you
  • Photographing artifacts is permitted, but do not photograph staff without their permission
  • No recording without prior written permission
  • No children under age 16, 16-17 with a parent or responsible adult
  • No "self-guided tours" or walkthroughs of the collection 
  • Visitors must stay with the group
  • Tour groups are limited to no more than 10 individuals


Tours of the Astronomical Photographic Glass Plate Collection are currently suspended. Ordinarily, Plate Stacks tours are restricted to Tues. 1-3 and Thurs. 10-12.

Tours of the Wolbach Library and the Observatory's Great Refractor led by the Head Librarian are also suspended. 


We are committed to supporting all visitors to the Observatory. Unfortunately we are constrained by the 19th (and 20th) century buildings in which our collections are stored. For this reason, please specify if your tour will include wheelchair users. We can provide virtual tours of the Plate Stacks and Great Refractor, along with the oportunity to view archival objects and ask questions, without entering inaccessible spaces.

Virtual Tours

The public can now explore these two historic facilities online.

Black and white image of a large historical telescope in an observatory dome.
Harvard College Observatory Great Refractor