While the Rare Books and Manuscripts department of MSEL has many wonderful books, there are other Hopkins libraries that also house older and rare works.
The John Work Garrett Library at the Evergreen Museum and Library contains 30,000 volumes that cover a wide variety of topics. Their natural history collection includes several important ornithological works, like the Audubon ‘double elephant folio' edition of Birds of North America. There is a strong collection of 16th- and 17th- century English literature and history featuring works by Shakespeare, Bacon, Milton, and Spenser. Other important collections focus on architectural history and American colonial travel and history.
The JHU Catalog includes the books at Garrett Library; you'll see the collection location of Garrett Library - Library Room. You need to make an appointment to use the collection (call 410-516-8348). Tours of the Evergreen Museum and Library are offered, but you can't touch the books on the tour.