The Pyramids of Giza: What Mysteries Remain?

More than 4,000 years after their construction, the pyramids at Giza in Egypt remain among the most recognizable ancient landscapes. When the Greek historian Herodotus wrote about their grandeur roughly 2,400 years ago, the pyramids were already ancient.

To this day, the Giza pyramids fascinate and even surprise archaeologists. New discoveries are still being made that hint at hidden entranceways and unexplained voids within the giant tombs. Here are some of the mysteries that remain.

The Pyramid of Menkaure—the smallest of the three main pyramids at Giza—is thought to have been built around 2500 B.C. as the tomb of the Fourth Dynasty pharaoh Menkaure.

Made with massive blocks of limestone and granite, the monument was likely about 215 feet tall when first constructed. But centuries of erosion and the removal of stone for other building projects have reduced it to about 200 feet.

When archaeologists first entered the Giza pyramids in the 19th century, they encountered structures stripped by ancient robbers. That left questions about what they originally contained—and how they were used. The original entrance passage for Menkaure was found hidden on its north face in 1837. The granite casing that once covered the pyramid’s lower section may have prevented looters from entering for centuries. However, the greatest discovery inside, an ornate sarcophagus, was lost in the Mediterranean Sea during transport.

Since the Giza pyramids are heavily protected by Egyptian law, only non-destructive research is now permitted. A 2025 study conducted by German and Egyptian archaeologists employed radar, electrical resistivity and ultrasound techniques to investigate a mysterious air-filled "void," detected beneath the Menkaure pyramid.

Images from a remotely operated camera suggest a void on the pyramid's east side might contain a hidden "second entrance." But the images also show no footprints or other evidence of human activity. Researchers are still unsure about the chamber's purpose.

A second void detected in a mortuary temple just east of the pyramid may hold religious statues of ancient Egyptian gods and perhaps of the pharaoh Menkaure himself, says Egyptologist Zahi Hawass, a scientific adviser for the ongoing exploration project. "People often hid statues inside temples at this time," he notes.

The detection of voids in the Menkaure pyramid will be explored further, says Harvard University Egyptologist Peter Der Manuelian, who runs the Digital Giza project: "It is certainly an intriguing discovery."

The findings at the Menkaure pyramid came only a few years after some of the same researchers used remote cameras to confirm the existence of an air-filled void within Giza's Great Pyramid, which was built for the Fourth Dynasty pharaoh Khufu around 2580-2550 B.C. The structure was about 481 feet tall when it was erected but now stands at about 455 feet.

A void was detected almost 10 years earlier by Japanese researchers who measured the strength of particles in cosmic rays that penetrate the ancient pyramid. A 2023 study revealed that this void, too, seems to be a hidden entranceway.

Evidence of an even larger void, located near the center of the Great Pyramid above the sloping passageway known as the Grand Gallery, was also documented in the 2017 study.

But Hawass explains that such voids may simply be relics from the pyramids' construction. They could have served as internal passageways or stress-relief cavities used to move stone blocks, redistribute weight or stabilize the structure as it rose.

He adds that his research—associated with the ScanPyramids project—will next study the middle-sized "Khafre" pyramid among the three main pyramids at Giza. That structure was built on a plateau for Khufu's son and stood over 470 feet high when it was constructed in about 2570 B.C. Today, it is about 448 feet tall.

The Giza Plateau, just west of Cairo, is home to about ten pyramids in total, although the smaller pyramids are overshadowed by the three largest. The entire country of Egypt has more than 120 ancient pyramids, but the ones at Giza have been famous since antiquity because of their immense scale.

Their size is due to the exceptionally good building materials available at the site, Hawass explains, including limestone of a quality unrivaled anywhere else in Egypt. Three different limestone quarries, one for each of the main pyramids, have now been found nearby.

Yet despite centuries of study, the pyramids continue to raise questions not only about lost chambers, but also about who built them and how such colossal stones were moved. Hawass is skeptical about claims that the Giza pyramids were built by an unknown ancient civilization.

He says one of their most important features is that they were built by the Egyptians themselves: "People need to understand how the Egyptians moved these 60-ton stones," Hawass explains. "This was a national project that ancient Egyptians participated in to make their king into a god." Separating myth from evidence remains central to modern research.

As new, non-destructive technologies allow archaeologists to peer deeper into these ancient monuments, researchers hope to answer long-standing questions while uncovering new ones.