Renowned as one of the most beautiful buildings in the world, the spellbinding Byzantine glory of the Hagia Sophia Mosque (Aya Sofya) is not only one of the top things to do in Istanbul, but also in Turkey.

Built by the Byzantine Emperor Justinian in 537 CE, it is renowned as the Byzantine Empire's greatest architectural achievement and has remained the world's largest church for 1,000 years.

The staggering bulk of its exterior is rimmed by the delicate minarets added after the Ottoman conquest, while the sumptuous and cavernous frescoed interior is a grand reminder of old Constantinople's might and power.

This famed monument is a must-do for every tourist visiting the country.