Exclusive | Inside Istanbul: Sneak Peek!

The Istanbul skyline is dominated by some 3,000 mosques and none is more famous than the Sultan Ahmed Mosque (better known as the Blue Mosque), the national mosque of secular -- but changing -- Turkey. The exterior of the mosque, completed in 1616, is stunning while the interior, like most houses of worship of Islam, is understated but still impressive.

Note: Visitors are not always allowed to photograph inside the Blue Mosque.