What if I wanted to build a Great Pyramid today?
Let's say that you want to create a theme park called Egypt World, complete with an authentic reconstruction of the Egypt's Great Pyramid as the centerpiece for your park. What would you have to do, and would modern technology make the project any easier?
If you wanted to be completely authentic about it, you would do the whole project with people-power. It's believed the great pyramid was built with the labor of 5,000, 20,000 or 100,000 people (depending on which expert is doing the estimate) over the course of 20 years or so. No matter how you slice it, that's a lot of person-years of effort. Even if you paid your workers minimum wage, just the labor of the project would cost billions of dollars.
The Great Pyramid is also amazing from a materials standpoint. The pyramid measures 756 by 756 feet at the base and is 481 feet tall. It is made up of more than 2 million blocks weighing on the order of 3 tons each. To build it out of blocks, you would have to find a quarry containing that much stone, cut the stone out of the quarry, load it onto a truck or a train, haul it to the site, unload it, lift it and so on. Working with stone blocks is definitely going to be a major pain. It's certainly doable, but it's a pain nonetheless.
There must be an easier way. Luckily, using today's technology, there is. To do it the modern way, you would definitely go with concrete. It would be something like building the Hoover dam, which has about as much concrete in it as the Great Pyramid has stone. With concrete, you can mold the shape you want and pour.