The funny thing is that in the 21st century, concrete can be quite light.

Well, there were people that made light concrete on the 20th century too. But not it's accessible to anybody.

Never mind placing it, bringing it to the place where it should be, er, placed might also be a challenge. Unless you can drive a forklift into your office...

I took it to the office on a little trolley thing

I didn't mean the laptop stand, I meant the concrete desk one of the parent comments suggested...

how much does it weigh? it looks like maybe 20-30lbs

Turtles all the way down.