In what ways was Constantinople a golden city?

From http://en.wikipedia.org/wiki/Constantinople

"Strategically located between the Golden Horn and the Sea of Marmara at the point where Europe meets Asia, Byzantine Constantinople had been the capital of a Christian empire, successor to ancient Greece and Rome. Throughout the Middle Ages Constantinople was Europe's largest and wealthiest city, known as the Queen of Cities (Vasileuousa Polis)."