A 1,768-km (1,100-mile) pipeline carrying oil from the Caspian Sea to the Turkish Mediterranean port of Ceyhan has been formally opened.
The $3.6bn (£2bn) pipeline crosses three countries
The Baku-Tbilisi-Ceyhan pipeline links Azerbaijan, Georgia and Turkey. Oil is then shipped to Western markets.
The US-backed project was conceived 10 years ago to diversify the West's oil sources and bypass Russia.
Oil began flowing in June. At full capacity the pipeline will carry a million barrels of crude oil a day.
A second pipeline carrying Caspian gas along the same route is expected to start working by the end of the year.
The presidents of Turkey, Azerbaijan and Georgia and ministers from a number of countries attended the official opening ceremony in Ceyhan.
The pipeline has been heavily backed by Washington from the very start.
The US is keen to challenge Russia's dominance of energy supply routes and to promote the Caspian as a secure additional source of fuel channelled via America's regional allies, says the BBC's Sarah Rainsford in Ceyhan.
For Ankara too this is a strategic project as much as an economic one, she adds.
Ankara is currently negotiating to host several other international gas and oil pipelines, hoping to become a major transit and terminal country for fuel.