Banco Central, Brazil

On August 6-7, 2005, a gang of robbers, allegedly Primeiro Comando da Capitaldug a tunnel towards Banco Central in Fortaleza from where they stole $70 million. The robbers managed to keep the security system silent and nobody knew anything about the robbery until Monday, August 8, when the bank was open.
The money from the safe were to be examined and either destroyed or put back into circulation. The bills had not been sequentially stored, so they became practically impossible to track.  Three months before the robbery, the thieves rent a nearby house and dug a 78 meter tunnel right under the bank.
The robbers were smart enough to give the impression that the house they had rented was the headquarters for a landscape company which sold natural grass, artificial grass and plants. The neighbours had seen that large earth quantities were carried away in a van daily but they thought that was a normal activity for such a business. The tunnel was 70 cm wide and four meter deep. It was well built; the walls were reinforced and had its own lighting and air conditioning systems.
In the last week, robbers dug through a 1, 1 m thick steel reinforced concrete to get to the bank’s safe. The bills weighed about 3, 5 tons. On October 22, the body of the presumed operation head, Luis Fernando Ribeiro, 26 years old was found on secondary road near Rio de Janeiro. The man had handcuff marks on his wrists. Other 5 men were arrested on September 28 carrying $5.4 million and they admitted to having dug the tunnel. Authorities have only been able to get back $7 million; the other $63 million are still missing.