A record number of runners will compete in the world's only transcontinental marathon on Sunday.
The Vodafone 40th Istanbul Marathon will start on the Asian side of Istanbul's July 15 Martyrs' Bridge, formerly known as the Bosphorus Bridge.
The finish line is located in the historic Sultanahmet Square on the city's European side.
This year's theme is: "Run Istanbul for a healthy future."
Around 30,000 professional runners, from more than 100 countries, will take part in the marathon.
In addition to that, about 100,000 people are expected to run in the 8-kilometer (5-mile) transcontinental Istanbul Marathon Fun Run.
The event features a 42-kilometer (26-mile) marathon, and three other races on courses of 15 km (9.3 mi.), 10 km (6.2 mi.), and 8 km (4.9 mi.). It will also include a race for wheelchair-bound participants.
About 5,000 runners -- more than half of them foreigners -- will compete in the 42-km marathon.
The top five countries sending runners are Russia, Germany, Ukraine, Britain, and France.
Fifty-five elite runners from Turkey, Kenya, Ethiopia, Azerbaijan, France, Bahrain and Morocco, will participate in the marathon.
Compared to recent years, the number of foreign runners in the marathon has doubled.
The Istanbul Marathon is among 17 marathons in Europe and 38 marathons in the world.
Vodafone is the main sponsor of the race organized by the Istanbul Metropolitan Municipality's Spor Istanbul company.
Last year, French runner Abraham Kiprotich won the men's category and Kenya's Ruth Chepngetich the women's category.
For more information, visit www.maraton.istanbul and follow the #runistanbul and #run4health hashtags on Twitter.