It’s no wonder that our fascination with the pyramids of Giza have endured for millennia. The massive Great Pyramid—built for the Pharaoh Khufu and finished around 2560 B.C.E.—is the only marvel of the original Seven Wonders of the Ancient World still intact. And the rest of the complex is nothing short of brilliant, too. Perched on the outskirts of Cairo, the Giza site contains six pyramids in total: three towering ones, including the Great Pyramid, and three smaller ones—plus an enormous statue of a sphinx, for good measure.

You’d think that a few thousand years on Earth would have revealed all of the pyramids’ mysteries by now, but it seems they still have plenty of secrets to share. As recently as last fall, new chambers were discovered in the Great Pyramid. And like any ancient sites worth their sand and stone, they’ve inspired passionate debates—not to mention a few conspiracy theories—over the years, too. Below are a few more facts you might not have known about these formidable structures:

The pyramids from the Giza Plateau. Photo: Getty Images

A Feast Fit for Kings:

Today, after centuries of erosion, the Great Pyramid of Giza stands about 450 feet high. (To put that in context, the Statue of Liberty tops out at 305 feet.) For nearly 4,000 years, it was the tallest building in the world—and it’s hefty, too. The pyramid was built with an estimated 2.3 million stone blocks, which weigh 2.5 to 15 tons each.

Clearly, constructing the pyramids required massive manpower. For a long time they were believed to have been built by slaves. But research from the past few decades suggests otherwise. In the village surrounding the pyramids, archaeologists discovered remains from enough sheep, cows, and goat for thousands of people to eat meat every day—meaning, says Harvard Magazine, “that the pyramid workers were fed by royalty… [and] they were not slaves at all, at least not in the modern sense.”

Shine Bright Like a Diamond:

Today, the Giza pyramids wear the tawny tones of their surrounding Libyan Desert. But back in their heyday, they sparkled. Originally, the pyramids were encased in slabs of highly polished white limestone. When the sun struck them, they lit up and shimmered. Some researchers believe that the pyramids’ capstones were plated in gold as well.

Those dazzling façades have long been stripped—some sources report that those blocks of stone were repurposed and used to build mosques—but you can still see remnants of a once-snowy cap atop the middle pyramid. (And you can see The Smithsonian’s rendering of what the pyramids looked like in their glory years.)