Credit: Glauco92 @ Wikipedia. CC-SA license.
This audiobook (MP3 format) is a recording of Cicero’s The Treatise on Friendship. It’s a good quality recording done by a single author, and was rescued from the now defunct eJunto, which was a project to publish audiobooks into the public domain.
You can download all the MP3 files as a single ZIP file (cicero—the-treatise-on-friendship.zip, 40 Mb), or you can browse the individual MP3 files.