Celebrities have backed library lovers in a series of "read-ins" in protest over threatened closures.
Save Our Libraries Day saw more than 100 events held across the UK to bring attention to proposed government spending cuts.
More than 350 libraries are understood to be under threat of closure.
The national day of campaigning saw authors including Philip Pullman and the musician Billy Bragg pledge their support to libraries.
As well as quiet reading, some events involved storytelling, writing workshops and music.
There was a flash mob book reading at Cambridge Central Library and at Leeds City Library demonstrators dressed up as their favourite characters from literature.
His Dark Materials author Pullman took part in an event at Oxford Central Library and Bragg took his guitar to Charmouth Library in Dorset.
Children's author John Dougherty went on a "flying authors" tour through several libraries in Gloucestershire while comedian Phill Jupitus worked as a librarian for the morning at St Aubyn Library in Plymouth.
Soprano Lesley Garrett attended an event in Bawtry, Doncaster, where she told people that libraries helped her get involved with classical music.
The Gruffalo author Julia Donaldson, who also pledged her support to the campaign, told Sky News: "If you close all these branches, get rid of these expert librarians, we're going to end up with a population of more illiterate people."