It was taken early on Tuesday, according to the Bavarian state police, from the Celtic and Roman Museum in Manching, which is located 60 kilometers (37 miles) north of Munich.
The 483 coins are regarded as the largest cache of Celtic gold recovered in the 20th century and were uncovered in 1999 during excavations of a historic town in Manchning.
According to the German news agency dpa, the coins, which combined weighed roughly 4 kilos (8.8 pounds), are worth several million euros, according to police (dollars).
“The loss of the Celtic treasure is a disaster,” it quoted Bavaria’s Minister of Science and Arts, Markus Blume, saying. “As a testament to our history, the gold coins are irreplaceable.”
He said the thieves had shown “incredible criminal energy.”
Police are appealing for witnesses who might have seen suspicious individuals near the museum or have other information that could lead to the recovery of the treasure.