Scales of Eberron
Flamekeep is the largest metropolis in Thrane, with a population of 150,000. However, nearly half of the 2.3 million people of Thrane live within the immediate region of the city. The city is the religious and political heart of the nation as well as the population center. In 299 YK when Tira Miron plunged her sword through the couatl and demon, creating the Silver Flame, Flamekeep was built around that Flame, and the cathedral later built from the keep. The city eventually grew around the holy site.
The Keeper of the Flame, Jaela Daran, ostensibly rules from here. The Council of Cardinals, in practical terms, runs the country from the city, though they are in fact subservient to the Keeper of the Flame; she seems primarily interested in spiritual rather than secular matters though. High Cardinal Krozen, in particular, has taken most of the secular administration of the nation into his purview and largely treats Thrane as his personal kingdom.