On January 2014, during a visit to the old city of Jerusalem, I used an excellent set of audio guides, provided by the Israel Ministry of Tourism. Each guide focuses on a specific walking tour such as, "The Jewish Quarter", "Via Dolorosa", "Mount Zion to Jaffa Gate", etc. The tours last a couple of hours and are informative and fun.
The guides can be downloaded unto any mobile device, and contain the audio, the text, and a detailed map of the walking route. In addition, I discovered that using a GPS-enabled device (such as my Nexus tablet), your current location is displayed on the route map. What a delightful feature. No more getting lost on a tour. When will Lonely Planet have it?
I downloaded the guides via WiFi at the tourism office located by the Jaffa Gate, but I failed to note the URL. If you know it, please post a comment.