The last American troops are expected to leave Bagram Air Base on Friday, as the base gets turned over to Afghan forces.

The U.S. withdrawal, after nearly 20 years, marks the end of the American presence at the enormous compound. Bagram Air Base once saw thousands of troops pass through and was the hub of all U.S. military activity in Afghanistan. 

At its peak in 2011, the U.S. had nearly 100,000 troops and 35,000 contractors in Afghanistan. Soon that number will be zero. The full withdrawal of U.S. troops from the country could be completed by this week.

The handover of Bagram Air Base to the Afghan military proceeded quietly with little fanfare, although a ceremony is planned for Saturday to mark the turnover.