In August 2005, a crew of thieves spent three months digging a tunnel underneath a busy city street in Fortaleza, Brazil, then busted their way into a bank vault and nabbed a whopping $67.8 million in cash. To date, police have recovered just $7 million. This is not uncommon: For many large-scale robberies, the entire amount of stolen loot is rarely found, leaving billions in missing currency, paintings, jewels, and gold bars floating in limbo around the world. Here are some highlights of the most infamous unsolved heists throughout history.
- Jack Boulware

1876
In January, New York thieves break into the new security system of the Northampton National Bank in
Massachusetts, stealing cash and bonds worth over $26 million today. A month later, they write a ransom note to the bank, offering to sell the bonds for cash. The bank negotiates for nearly a year before detectives arrest and convict the gang. The money is never recovered.

1945
As Hitler's empire collapses in April, the infamous Nazi gold collection, $3.34 billion worth of gold bars, stolen foreign currency, and jewels, suddenly disappears from Reichsbank vaults. It is called the world's largest bank robbery in history. Over the years, portions are found in Switzerland, Portugal, Spain, Sweden, and Turkey, but much of it remains missing. Search teams still hunt for Nazi gold - from the coast of Greece to bank vaults in Brazil
to the bottom of an alpine lake in Austria.

1950
In January, after two years of planning, armed robbers use copied keys to break into the "burglar-proof" Brinks Building in Boston. They nab $2.7 million in cash, checks, and money orders. The Great Brinks Robbery is labeled "the crime of the century." It takes until 1956 to charge and sentence eight of the thieves. Rumor has it that the money is hidden in the hills outside Grand Rapids, Minnesota.

1963
In August, 15 men tamper with train signals and stop the Glasgow-to-London mail train, stealing £2.6 million without firing a shot. Thirteen suspects of the Great Train Robbery are arrested and imprisoned. Three escape jail and become folk heroes - one of whom gets his life made into a movie starring Phil Collins. The lost money was never recovered.