"Lethal Weapon" redefined action movies for a generation with the antics of Riggs (Mel Gibson) and Murtaugh (Danny Glover). Helicopter shoot-outs and drive-by killings as well as a healthy dose of exploding buildings add up to a high-octane buddy cop movie that made us think twice about what makes an action movie.

But then "Lethal Weapon 3" dialed it up a notch.

He may be too old for this sh**t, but just a week from retirement, Murtaugh finds himself dragged into a case surrounding a former LAPD lieutenant turned arms dealer who's been giving up armor-piercing weapons to local gangs. Cue the shootouts and chase scenes we all love as Riggs and Murtaugh get on the case. But there's one scene at the very beginning of the movie that's easily the most memorable — when Riggs and Murtaugh accidentally blow up the ICSI office building. And it turns out, that was no special effect.

I'm Thinking We Should Cut The Blue Wire

"Lethal Weapon 3" has one of the best opening scenes in action movie history, with the crime-fighting duo discovering a bomb in a car at the ICSI building … and hilariously bickering about what to do with it.

Murtaugh is keen to hightail it out of there and let the bomb squad do their thing, but Riggs knows exactly what he's doing … sort of … and decides to defuse it himself. There's a brilliant exchange between the two as Riggs changes his mind about which wire to cut. Red or blue? "There, all done," he says as he snips the red wire. But the timer begins to countdown even faster.

Cut to Riggs and Murtaugh sprinting out of the building as the windows blow, the office is engulfed in flames and the ICSI building comes toppling down. It's a high-stakes way to start the "Lethal Weapon" sequel, and it really hammers home why Murtaugh is ready to retire.

The best thing though? It was never in the script … and only came about because of a real-life building demolition.

Doing It The Old-Fashioned Way

The ICSI office building we see in "Lethal Weapon 3" isn't a set or a miniature. It was the real-life former City Hall of Orlando, Florida. So, how the hell did it end up being blown up for an action movie?

During an interview with Empire, director Richard Donner explained how it happened:

"Sometimes things would just come along. When we were prepping the third movie, we got a letter from the film department of Orlando, Florida, saying they were going to blow up their old city hall … They said, 'Can you use it?' Well, s**t, we already had a script, but we weren't going to turn that down."

Thankfully, Warner Bros. agreed that this was an opportunity too good to waste and paid $500,000 to pay for the building's demolition. Then, Donner worked the demolition into the movie's opening scenes, as the ill-fated bomb-defusing at the ICSI office. And it sounds as though it was an absolute blast to film.

Riggs? Murtaugh? Get The F**k Out Of Here

The former City Hall stood at the intersection of Orange Avenue and South Street in Downtown Orlando. But blowing up an entire building is no small feat, and according to Gibson, it took the team over a month to rig the building with explosives. Donner explained how the whole thing came together:

"We did the explosion in pieces. When you guys ran out of the building, we blew all the glass. And you were really there when the big detonation happened. I'm sure you felt that blast."

That's right — Mel Gibson and Danny Glover were actually there, running out of the entrance to the former City Hall as the windows blew, then clambering to safety as the building was detonated. "We were jumpy as hell," said Gibson. "We knew the building was coming down and we were ready to sprint. When we took off, I thought, 'I'd better slow down for him' — but he actually ran right past me."

The result is a heart-stopping piece of cinema with Riggs and Murtaugh narrowly escaping the collapsing building. And it's more real than any explosive stunt you'll see.

You Really Ought To Learn To Trust Your Instincts More, Rog

The demolition, rigged to look more like a bomb explosion, was a huge success and the scenes add a certain realism to the over-the-top antics of Riggs and Murtaugh. But if it wasn't for the Orlando film department, this scene would never have been shot. As a thank you, then Orlando mayor Bill Frederick was given a cameo in the movie, as the Bomb Squad member who sarcastically claps and says "Bravo" to Riggs and Murtaugh as they cower behind their car.

As for the former City Hall, it eventually became the plaza for the new City Hall, which had already been built behind the "ICSI offices" at the time of filming. The explosives had been rigged to cause the building to collapse forward, reducing the chances of damaging the new building.

Now, a water fountain and monument stand in its place. But the building's destruction lives on as one of the craziest, most memorable action sequences of the "Lethal Weapon" series, and a peak moment in one of Richard Donner's best movies.

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