BERLIN — Until it disappeared under the darkness of night, the 220-pound gold coin sat behind bulletproof glass in Berlin’s Bode Museum.

Since December 2010, the gargantuan coin delighted museum visitors, who likely could not imagine the absurdity of transporting such a weighty hunk of money. Early Monday morning, however, thieves appear to have done just that.

“The coin was stolen last night,” museum spokesman Markus Farr told Reuters. “It’s gone.”

If so, how it was stolen remained a mystery early Tuesday morning. Berlin police stayed fairly mum on the museum heist, offering only a few tantalizing details that resembled the plots of the “Ocean’s Eleven” films.

The museum’s back wall backs up to passing railroad tracks. Perched about four yards above the tracks was a window leading to the museum, which police found ajar, the New York Times reported. Near the open window, they found a ladder that may have been used in the robbery, police told CNN

“Based on the information we have so far we believe that the thief, maybe thieves, broke open a window in the back of the museum next to the railway tracks,” police spokesman Winfrid Wenzel told Reuters. “They then managed to enter the building and went to the coin exhibition.”

The working theory, as the New York Times noted, is that thieves dragged the coin through the museum then along the railroad tracks, likely to a nearby park. How they would have avoided any further security systems or cameras remained unclear, as police declined to comment further.

There was, though, little doubt that the coin was a specific target. The bulletproof glass encapsulating the coin “appeared to have been violently shattered,” Wenzel said. Meanwhile, the other coins in the display remained peaceably untouched.

The Royal Canadian Mint produced its first $1 million (Canadian) gold coin in 2007. One one side appeared the head of Queen Elizabeth II. The other side bore the image of a maple leaf.

Nicknamed the “Big Maple Leaf,” the coin boasts impressive metrics: it is 99.999 percent pure gold, more than an inch thick and its diameter exceeds 20 inches. It was featured in the Guinness Book of Records for its “unsurpassed purity,” CNN reported. The coin’s face value is a misnomer. Given its gold content, it is actually worth around $4.5 million.

Pleased with its creation, which the Royal Canadian Mint’s website called, “a true milestone in minting,” the mint then decided to produce up to 10 copies “after several interested buyers came forward.” Eventually, it settled on producing five replicas, one of which landed in (and subsequently disappeared from) the Bode Museum.

“Why did the Royal Canadian Mint make the world’s purest and largest gold bullion coin?” a statement on the mint’s website said. “Because we can.”

Selling such a notable coin on the black market would prove difficult, of course, unless one first melted it down and sold the crude gold comprising it.