Iron Gate, a narrow gorge of the Danube River on the border between Romania and Serbia and Montenegro. It is about two miles (3 km) long. For centuries it was a serious obstacle to navigation. The first major improvement came in the late 1890's with the blasting of a channel (the Sip Canal) through boulder-strewed rapids in the river. In the early 1970's, the Iron Gate dam was completed at the lower end of the gorge. It was built jointly by Romania and Yugoslavia (now Serbia and Montenegro), and is one of Europe's largest producers of hydroelectric power. Its electrical output is evenly divided between the two countries. Locks on either side of the dam have further improved navigation. The dam is also used for flood control. A short distance upstream from the dam is Lepenski Vir, the excavated site of Europe's oldest known settlement, which dates from about 6000 B.C. The gorge is noted for its scenic beauty.