The Bank of Karabraxos was a financial institution used by the ultra-wealthy of the galaxy. It was the most secure bank in the galaxy: no one stepped foot on the planet without protocols, all movement was monitored, air consumption was regulated and DNA was required at every stage. Therefore extremely valuable items were stored in the bank as well.
The bank made use of the Teller, a creature that could detect guilt. If there was an intruder, the Teller would scan the suspect's mind for criminal intent and if found, it would liquefy their brain. According to Head of Bank Security Ms Delphox, the person's next of kin would be informed and incarcerated.
The bank was run by Madame Karabraxos, who lived in the private vault. She used clones of herself as administrators. If they displeased her, she would have them incinerated.
At the behest of a future Madame Karabraxos, the Twelfth Doctor, Clara, Saibra and Psi broke into the bank to free the Teller and his mate. Shortly after, the bank was destroyed in a solar storm. (TV: Time Heist)