Project Gutenberg is a library of over 60,000 free eBooks which you can download or read online. It is mainly a collection of older works for which copyright has expired.
Open Library has more than one million free e-books available and provides online access to many public domain and out-of-print books.
Internet Archive is a non-profit library of millions of free books as well as other media resources.
The British Library holds a number of free online collections for English and History. These include academic articles and digitised manuscripts.
The UK Web Archive (UKWA) collects millions of websites each year, preserving them for future generations. Use this site to discover old or obsolete versions of UK websites, search the text of the websites and browse websites curated on different topics and themes.
The Guardian lists a selection of virtual tours which allow you to view thousands of paintings, sculptures and installations online – many in minute detail – as well as explore the museums themselves.