Is it true that we wouldn't be able to rebuild the pyramids today?

 Actually, we could. But no one would be willing to pay for it.

The Great Pyramid of Giza was built around 2600 BC.
By the time Cleopatra, the last queen of Egypt, died, the pyramid was already over two and a half millennia old. It remained the world's tallest building for about 3800 years, until it was dethroned by Lincoln Cathedral in 1311, although in other respects it dwarfs the Cathedral and most modern buildings.

I say all this to give you a sense of perspective. For thousands of years, people have looked at the pyramids and wondered how they were built.

Nothing like it had been built before or since. They were filled with indecipherable hieroglyphics, a product of an ancient and unknown culture. Their constructions have even been attributed to giants, angels, or aliens.

It's all because they were so incredibly huge, and for a long time, no one had any idea how they were built.
But with the deciphering of hieroglyphics and the advancement of archaeology as a field of study, we now have a good idea of ​​how they were built.

The pyramids were great public monuments of a wealthy civilization with an abundance of surplus labor.

They cut blocks of stone and floated them down the river.

They organized hundreds and thousands of workers and moved the blockades.

They placed them in a pyramid shape, because it was the simplest shape the structure could take.

There is nothing technically challenging about pyramids, except organizing so many people toward a single goal.

These were built in honor of deities. But they were still built with simple tools and simple methods.
If you could somehow organize that many people again, there's nothing stopping you from building another pyramid.

And if you had the money, you could just use modern equipment to build them 100 times faster.

How were the Egyptian pyramids built with such precision, and how was it possible to do so without modern tools or technology?

 First of all, look here: it's the top of the great Pyramid.

This is another view, where the individual blocks can be distinguished.

As you can see, precision isn't exactly the right word to describe the pyramids.

They were built with the precision one would expect from an organized and educated Bronze Age culture. No more, no less.

There are spaces between the blocks that were filled with sand and rock, and some spaces are large enough to fit an entire arm. The "millimeter" precision of the pyramids is largely a myth. Like a modern contractor, they focused on only a few parts, such as the outer layer of high-quality white limestone from Tura.

Meanwhile, this crack at the top of the pyramid, which is barely visible from the ground, looks like this:

They did their best and it's wonderful, but it's not exceptional precision.

Are the pyramids in Egypt safe to climb?

 No, absolutely NOT safe. In fact, climbing a pyramid can get you KILLED. Actually, climbing to the top isn't a problem - getting to the bottom is. A good friend of mine died from falling from the Great Pyramid of Giza in 1980 while studying abroad. In tragedy, I climbed it earlier that day with some other friends. Without a serious fear of heights, it is not very difficult for someone in reasonable condition to climb in 10–15 minutes.

But on the way down, you essentially have to jump down, stone by stone. Jump, jump, jump, hundreds of times. Remember, the pyramids were originally covered in polished limestone; they weren't designed as stairs. What's left are the ragged remains after looters removed the limestone layers to build the structures. The stones in the pyramids are uneven, ranging in size from a few feet to over 6 feet (see photo below).

Many of the footholds are smooth, slippery, and covered in sand dating back 4,000 years. The rocks can be slanted downward, too narrow, or cracked . There are few reliable handholds. With no fear, the climb feels fun and not life-threatening for those younger. While climbing, it never occurred to me that a small misstep could be fatal.

Imagine climbing the outside of a 45-story building without safety equipment. You really can't understand exactly HOW dangerous it is until you're up there and in serious danger. Imagine jumping off a ledge outside the window of a 35-story office building. I kept climbing to the top, but about three-quarters of the way up, I turned around and looked down, then immediately changed my mind. The 100-meter view straight down was dizzying.

My friend was quite athletic, but he slipped on the way down. This could have happened to anyone, as the terrain is steeper than it looks, so once you lose your footing, you won't stop falling until you reach the bottom.

[ Update : I just learned from some of my friends from the 1980s that climbing was already illegal at the time, but they bribed the security guards to keep them quiet. Interesting, no wonder no one bothered me when I climbed.]

Here's the view from the climb, near the top:

View from the bottom up:

What is the biggest discovery that archaeologists found in the pyramids?

 The most significant discovery inside the Great Pyramid wasn't gold or a mummy. It was crude, red-ochre graffiti hidden in a pitch-black chamber no human was ever meant to see.

Most pyramids were thoroughly looted thousands of years before modern archaeology even existed. When explorers finally penetrated the King's Chamber of the Great Pyramid, they found only a massive, empty granite sarcophagus. But in 1837, an Egyptologist named Howard Vyse blasted his way into the "relieving chambers"—five small, structural rooms stacked above the King’s Chamber. These rooms were designed solely to distribute the immense weight of the masonry overhead and were completely sealed during construction.

Inside these unlit spaces, Vyse discovered graffiti left behind by the ancient builders. The workers had painted names, dates, and accounting marks on the massive limestone blocks before they were hauled into place.

While this might not sound as glamorous as finding a solid gold death mask, the graffiti provided something far more valuable to historians. The marks included the names of the specific work gangs, such as "The Friends of Khufu Gang."

These markings struck a fatal blow to the enduring myth that the pyramids were built by enslaved people. The casual, almost boastful nature of gang names points to organized teams of skilled laborers, likely conscripted citizens who were well-fed, housed, and proud of their monumental task. Furthermore, the presence of the pharaoh Khufu's cartouche inside permanently sealed structural voids conclusively dated the pyramid to his reign, silencing centuries of wild speculation.

Archaeologists have made many remarkable finds around the pyramid complexes, from the intact 143-foot wooden solar ship buried at the base of Khufu's monument to the recent discovery of hidden internal voids using muon radiography. Yet, it is the simple red paint of the builders' graffiti that remains the most illuminating find. It reached across millennia to replace myths of forced labor with the real voices of the people who actually stacked the stones.