In their newly published book Los Reyes del Grial (“The Kings of the Grail”), medieval history lecturer Margarita Torres and art historian José Miguel Ortega del Rio claim the Holy Grail rests inside the Basilica of San Isidoro in the northern Spanish city of León. The historians say that a three-year investigation led to their conclusion that the hallowed cup that Jesus Christ supposedly drank from at the Last Supper and that was used to collect his precious blood is a jewel-encrusted goblet that has long been known as the chalice of the Infanta Doña Urraca in honor of the daughter of King Ferdinand I, ruler of León and Castile from 1037 to 1065.

The researchers had been investigating Islamic remains in the Basilica of San Isidoro when they came across medieval Egyptian parchments that mentioned that the holy chalice had been taken from Jerusalem to Cairo and then given to an emir who ruled an Islamic kingdom on Spain’s Mediterranean coast in return for the help he gave to famine-stricken Egypt. The emir then gifted the chalice as a peace offering to the Christian King Ferdinand. The goblet has been in the basilica’s possession since the 11th century and in plain sight in the church’s basement museum since the 1950s.

The chalice, made of gold and onyx and sprinkled with precious stones, is actually two goblets fused together, one turned up, the other down. Torres and del Rio say the upper half is made of agate and missing a fragment, exactly as described in the Egyptian parchments. The co-authors report that scientific dating has placed the origin of the cup between 200 B.C. and 100 A.D. As the Irish Times reports, the co-authors concede they cannot definitively prove that the chalice actually touched Jesus’s lips, only that it is the vessel that early Christians revered as the one used at the Last Supper. “The only chalice that could be considered the chalice of Christ is that which made the journey to Cairo and then from Cairo to León—and that is this chalice,” Torres told the newspaper. Since the book’s publication last week, the basilica has been inundated with visitors, forcing curators to remove the relic from display until they can find a larger exhibition space to accommodate the crowds.

This, of course, is not the first time that the Holy Grail has been “found.” For while the Holy Grail has proven elusive, it is also strangely ubiquitous. From Latvia to Scotland, more than 200 goblets in Europe alone have been posited as being the holy relic. Some claim the cup rests in the sewers of Jerusalem while others believe that the medieval Knights Templar took the goblet from Jerusalem during the Crusades and eventually secreted it away in New World locations ranging from Minnesota to Maryland to Nova Scotia. Some theorize it is even hidden inside Fort Knox.

Numerous times in the past century, newspaper headlines similar to the ones today declared the quest for the Holy Grail over. In the early 1900s, it was supposedly discovered near England’s Glastonbury Abbey. A few years later, a battered silver goblet with elaborate ornamentation unearthed in the ancient city of Antioch was put forward as the Holy Grail. The Antioch Chalice, now in the collection of New York’s Metropolitan Museum of Art, toured museums such as the Louvre in Paris and even went on display in the 1933-1934 World’s Fair in Chicago before it was dated to the early sixth century. In 1927, a chalice with Greek inscriptions in possession of the Toledo Museum of Art even led one newspaper to declare, “Toledo Has Claims to Holy Grail.”

Many historians are skeptical of the latest claim of the Holy Grail’s discovery, and there’s no evidence that the Holy Grail even exists. The cup received only a passing mention in the Bible, and its religious significance didn’t arise until medieval legends entwined ancient Celtic myths with the Christian tradition of the Holy Chalice used by Jesus at the Last Supper. “The Grail legend is a literary invention of the 12th century with no historical basis,” Carlos de Ayala, a medieval historian at a Madrid university, told the AFP news agency. “You cannot search for something that does not exist.”

Even if there is a Holy Grail, proving that it indeed was the goblet used by Jesus would be nearly impossible. One thing that’s all but certain, however, is that in spite of the latest announcement, history’s greatest treasure hunt will continue.