Moscow this year is celebrating the 80th anniversary of its subway system — the Moscow Metro — a crowning achievement of the Soviet Union's unprecedented forced industrialization in the 1930s.

One of the world's biggest and busiest subways today, it has dark connections to the repressions of Soviet dictator Josef Stalin.

To celebrate, Metro officials launched a series of commemorative events. One of the most popular was a parade of vintage subway trains — the oldest of them dating from 1935, when the first section of the Moscow subway was completed.