It's official – a Lego tower can only be 2.17 miles (3.5 km) tall before its weight crushes the brick it is standing on. Engineers put their effort into calculating what the theoretical limit would be for the height of said tower.
They took into account the fact that the brick is 2x2 inches (5x5 cm), which, even if manufactured out of ABS plastic in Lego's factories, can hold up to 950 pounds (430 kg).
A hydraulic testing machine was used to test the pressure applied on the first Lego brick. The experiment resulted in the fact that you could add 375,000 bricks and put them on top of one another, without the first one breaking.
Of course, this experiment is only possible in theory, as, in real-life, men are not able to place bricks one on the other in perfect symmetry, Gizmodo