Look at how fractured the government and political systems of the west have become. Humans forget. We've forgotten how to build pyramids, we've forgotten the second world war and the lessons learned.
What exactly has led you to believe this...?
^ well, maybe some problems like any project, but they would overcome them.
I have a similar feeling looking at the great cathedrals.
These structures took up a huge proportion of the community's money, labour and talent, for decades on end. They're orders of magnitude bigger than any 'normal' building of the time or for centuries later. All with no prospect of any tangible return.
If we set out now to build the largest structure that the limits of our technology allow, designed almost purely as a work of art with little regard to any function, what would that look like? I don't know, no-one's done it for centuries.
The closest thing is the Eiffel Tower. It's a national icon, the wrought-iron equivalent of a pyramid - but it took two years to build, not twenty. What would an Eiffel Tower with 10x the resources look like? And that's more than a century ago.
It's not hard to believe that humans could build these things, but it's occasionally hard to believe that they chose to.
Great pyramid: 5 or 6 million tons
So only around 500 times as much moving material around, feasible I guess. You might need a dedicated rail line built direct to the quarry.
Funny to mention cathedrals considering that they finished one in Spain just recently. There's also Guédelon Castle in France, still being slowly built.
Working with blocks of this size is just not a problem for modern equipment.
I suppose the Burj Khalifa, the Sky Tree, the Sphere, and the Luxor don't count? Mount Rushmore? The only thing that's changed is that we've gotten more efficient at megaprojects and, I suppose, they've become so common you don't register them as interesting anymore.
- Luxor in Las Vegas: https://commons.wikimedia.org/wiki/File:Las_Vegas_Luxor_04.j...
- Bass Pro Shop Memphis Pyramid: https://commons.wikimedia.org/wiki/File:Memphis_Pyramid.JPG
- Sunway Pyramid Mall, Malaysia : https://commons.wikimedia.org/wiki/File:Sunway_Pyramid_front...
- Walter Pyramid, Cal State Long Beach: https://commons.wikimedia.org/wiki/File:Csulb-pyr1.jpg
- Muttart Conservatory, Edmonton: https://commons.wikimedia.org/wiki/File:Muttart_Conservatori...
- Palace of Peace and Reconciliation, Kazakhstan: https://commons.wikimedia.org/wiki/File:%D0%9C._%D0%90%D1%81...
The Burj Khalifa.
Luxor in Vegas is way more complicated than the egyptian pyramids were.