The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Noho Ltd.:
Travel 500 years back in time with the Dublin City Walls Lite iPhone app! See ancient towers, gates and prisons reappear in breathtaking 3D. Fly over rooftops, explore ancient landmarks and trace the original city wall on a stunning 3D model.City Walls Lite contains spectacular graphics, videos, photos and 3D animations that bring the medieval world to life like never before. Based on the popular Medieval Dublin boxset, the app will excite and delight viewers of all ages.
