Visitors swamped the museum at the San Isidro Basilica in Spain after two authors published a book claiming a goblet at the basilica is the Holy Grail. It’s not clear yet if the basilica was informed of the stunt prior to publication of the book, or if they were able to raise (or start charging) admission rates before the crowds arrived. Probably not, since they were unable to cope with the demand to see the goblet and have temporarily taken it off display.
Take your pick of news reports covering the story, like this one at the Guardian.
If you need to see The Holy Grail and can’t make it to San Isidro, you can visit the Cloisters Museum in New York City and view another The Holy Grail, a.k.a. the Antioch Chalice, which is either the real Grail, or maybe a lamp. The provenience of that one seems a bit sketchy, too.