In pictures: The rise and fall of the Berlin Wall

In the early 1960s, East German officials had a problem on their hands: In the years since the end of World War II, millions of their citizens had fled the communist state for neighboring West Germany.

Their answer? A barrier that would slice through Berlin, sealing off East Germany -- and East Germans -- from the West.

On August 13, 1961 citizens awoke to find a makeshift barricade of barbed wire and cinder blocks slicing through their city. Over the next three decades, it evolved into a 28 mile (45 kilometer) concrete wall fortified with watchtowers, electric fences, and armed guards.

The wall symbolized the deep ideological divide between the Soviet bloc and the West at the height of the Cold War.

But as the 1980s drew to a close, Communism's grip on the Eastern bloc slipped. Revolutions in Poland and Hungary paved the way for massive demonstrations in East Germany.

On November 9, 1989, the state opened its borders with West Germany.

This week marks 30 years since that momentous day, when crowds of East and West Berliners jubilantly clambered onto the wall, chipping away at both its graffitied (Western) and unadorned (Eastern) sides. The following year, Germany was officially unified.

Decades later, ghostly reminders of the wall that divided the city remain.