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 UIEvolution, Inc.:
Exciting and historical Cairo, Egypt, one of the birthplaces of civilization and home to some of the biggest wonders of the known world. A town where anything can happen! Come discover all that Cairo has to offer in this special application that takes you through the common and uncommon sights of this amazing place. "Top 25: Cairo", brought to you by the notable 'Top 25' series by UIEvolution, is an interactive application that allows you the chance to discover, read, and plan your trip. With an easy-to-use instant phone call feature, you can quickly call landmarks and begin researching and possibly planning your trip to Cairo, Egypt! And once you visit, you can start bragging to all of your friends and family on where you've been with the easy-to-use Facebook integration! Come discover more about Cairo, Egypt with Top 25: Cairo!