The Grand Bazaar. The Blue Mosque. Galata Bridge. Topkapi Palace. Hagia Sophia. Overwhelming, immense and really old, Istanbul is one of those cities where you can diligently explore for days and days on end and still not see everything you set out to see. It's a city where you need to pace yourself — and arrive with a battle plan.
Visitors more keen on ancient works of infrastructure than houses of worship should place the magnificent Valens Aqueduct on the top of their must-visit list. Arguably the most iconic water-related structure next to the Basilica Cistern in the continent spanning Queen of Cities, Valens Aqueduct — Bozdoğan Kemeri in Turkish or "Aqueduct of the Grey Falcon" — is a real-deal Roman aqueduct commissioned by Emperor Valens in the late fourth century to supply water to then-Constantinople. While Constantinople itself has, ahem, changed hands a few times since the aqueduct's completion, what remains of it has been seamlessly integrated into the modern fabric of cat-ruled Istanbul. Nowhere else is the intersection of antiquity and modernity quite as dramatic (and literal) as the much-photographed point where the aqueduct's double-decker span soars above bustling Atatürk Boulevard with traffic passing right through the structure’s monumental limestone arches.