The Answer To A Burning Question
The BBC magazine did to the work to find out How tall can a Lego tower get?
The average maximum force the bricks can stand is 4,240N. That’s equivalent to a mass of 432kg (950lbs). If you divide that by the mass of a single brick, which is 1.152g, then you get the grand total of bricks a single piece of Lego could support: 375,000.
So, 375,000 bricks towering 3.5km (2.17 miles) high is what it would take to break a Lego brick.
Anyone who has stepped on a Lego brick knows they don’t break easily [and hurt like hell if you aren't wearing shoes]. That just accounts for the downward force, and any lateral pressure would topple the single stack before you needed a ladder to add bricks to the top.
I know someone who literally has a ton of Lego bricks that represent his father’s collection, and then additions by various relatives. He does create rather large structures.