Scientists Discover Hidden Chamber Inside Egypt's Great Pyramid of Giza

"It was a big surprise," one of the researchers said.

Scientists have discovered a chamber hidden deep inside the largest and oldest of Egypt’s pyramids, marking the first major space to be exposed inside the renowned Wonder of the World in more than 200 years.

An international group of researchers stumbled upon the 30-meter-long, or nearly 100-foot-long, hollow opening inside the Great Pyramid of Giza, according to an article published Thursday in the journal Nature.

Authorities hope the discovery will help them better understand how the colossal, 4,500-year-old structure was built.

Three rooms inside the limestone and granite pyramid had previously been discovered: The chamber of Pharaoh Khufu, for whom the pyramid was built, a smaller queen’s chamber and a sloping passageway called the grand gallery.

“These large chambers were discovered in the ninth century A.D. and explored extensively by Western archaeologists in the nineteenth century,” Nature wrote. “But enthusiasts have wondered ever since whether there might be more hidden chambers inside the pyramid, or even whether the king’s real burial chamber is yet to be found.”

Scientists working with ScanPyramids, a mission under the French Heritage, Innovation and Preservation Institute, the Faculty of Engineering of Cairo and the Egyptian Ministry of Antiquities, made the considerable discovery while tracking particles called muons.

Muons are produced when cosmic rays strike atoms in the upper atmosphere.

Researchers placed a series of detectors that spot such particles in the queen’s chamber to reveal what was stone and what was empty space.

After several months, they got an “unexpected line,” Mehdi Tayoubi, president of the Heritage, Innovation and Preservation Institute, told Nature.

The purpose of the space is unknown, but Tayoubi suggested it may have served as a “second Grand Gallery.”

Some experts suggested the pyramid’s architects designed the space to maintain its structural integrity.

Researchers have no plans to drill into the chamber, but are developing a tiny flying robot that they may one day send in to explore.

“It was a big surprise,” Tayoubi said of the discovery. “We’re really excited.”