12,368 square kilometers

Photo from Wikimedia Commons
Sydney Metropolitan Area
Australia's largest city, spread around one of the world's great harbours/Cities & Urban
The Sydney metropolitan area covers about 12,368 square kilometers, making it one of the most sprawling cities in the world by area despite having a population of about 5.3 million. The city is built around Sydney Harbour (Port Jackson), one of the largest natural harbours on Earth, spanned by the iconic Sydney Harbour Bridge (1,149 m long). Sydney's urban area stretches about 70 km from east to west and 60 km north to south, bounded by the Blue Mountains to the west and the Pacific Ocean to the east.
Measurements
Coast to Blue Mountains
Urban spread
Including approach spans
Main steel arch
55 square kilometers of waterway