The Boston Public Library reopened its special collections department of rare books and other historic items on Tuesday after the completion of a $15.7 million renovation project, city officials said.

The collection, which includes a copy of Shakespeare’s First Folio and original printings of the Declaration of Independence, is held at the central library in Copley Square.

“We are so lucky to have historic books and manuscripts on display at the Boston Public Library, and with that comes a responsibility to take care of these works and make them easily accessible,’’ Mayor Michelle Wu said in a statement. “I’m thankful to the BPL and all who made restoration of the Special Collections possible for future generations of Boston residents to enjoy.’’

Wu also praised the renovations in an interview at the library on GBH Radio.

“We have some of the foremost gems of our country’s intellectual history right here in this building,’’ she said. “And if you go in the back, there’s now wide-open windows where you can see where they preserve it. ... It’s like a science lab in parts of it. It’s really incredible, the work that happens here.’’

The project was financed by the city and a collaboration between the library, the city’s public facilities department, and Finegold Alexander Architects, officials said.

The project included 31,000 square feet of renovations, including a new reading room and lobby, better storage for rare books and manuscript collections totaling nearly seven miles of specialized shelving, new staff workspaces, a conservation lab, and fire suppression system, officials said.

The improvements will ensure the long-term preservation of the library’s collections and their continued public access, officials said. The new space was designed to encourage patrons to visit and “engage with the storied collection,’’ they said.

Boston Public Library president David Leonard thanked the city for funding the renovations.

“The BPL can once again provide full service to our Special Collections’ treasures and continue stewarding the Rare Books and Manuscripts collections in our newly renovated world-class space, accessible to all, both in-person and online,’’ Leonard said in the statement. “The historic items in this collection belong to the people of our city, and we look forward to sharing them with our community and the world.’’

The special collections include an impressive array of rare books, manuscripts, prints, archives, music, fine arts, and photography, officials said.

Notable items include a copy of Shakespeare’s First Folio; Robert McCloskey’s sketchbooks, including his preliminary drawings for “Make Way for Ducklings’’; four original printings of the Declaration of Independence; the complete run of the abolitionist paper The Liberator; 350 works by artist Henri de Toulouse-Lautrec; and the Robert Aitken Bible, the first complete English-language Bible printed in America.

“We are thrilled to welcome visitors into the newly renovated Special Collections spaces,’’ said Beth Prindle, the library’s head of special collections. “As it says on the side of the McKim building, we are dedicated to making these treasured items ‘Free to All.’’’

During the renovations, the library’s rare books and manuscripts collection was moved off site and stored securely for more than four years.

More information on the collections is available on the Boston Public Library’s website.

Travis Andersen can be reached at travis.andersen@globe.com. Follow him on Twitter @TAGlobe.