It took more than 2,000 pounds of explosives to bring down this 32-story tower in Frankfurt yesterday—roughly the same amount as a Mark 84 bomb. Thankfully, since we live in the age of YouTube, there are plenty of astounding videos of the demo.

A controlled implosion like this is way more difficult than it sounds. It takes careful planning in order to bring a massive building directly down into its own footprint, rather than outwards into the surrounding city. In the weeks leading up to yesterday's blast, the 380-foot-tall concrete tower was drilled with 1,500 holes—each carefully packed with explosives, calculated to bring the building down in several distinct phases.


Image: Thomas Lohnes/Getty.

The end result? The building falls inward so that the rubble collects at its center, as How Stuff Works explains:

The blasters set the explosives so that each "tower" falls toward the center of the building, in roughly the same way that they would set the explosives to topple a single structure to the side. When the explosives are detonated in the right order, the toppling towers crash against each other, and all of the rubble collects at the center of the building.

Before it was imploded yesterday, the tower housed a number of departments at the Johann Wolfgang Goethe University. Built with the flourishes (er, or lack thereof) of classic 1960s Brutalism, it was by all accounts a terrible building from the start. Overcrowded, there were often 20-minute-long waits for the elevator. In 2005, a woman was killed when she got stuck between floors. The decision to demolish the building seems to have been a rare case where nearly everyone agreed—you can hear the crowds cheering in most of the videos of the demo.


The sight and sound of the blast were intense—but those, too, were tightly controlled: The demolition engineers blew up canisters of water along with the explosives, which helped to control both the sound waves and the massive amount of dust that resulted. [Deutsche Welle]