The Bristol Catacombs are a real place underneath Bristol. They are also called "Redcliffe Caves" and are man-made caves just off the quayside. There are red sandstone caves in it. In 1665 a family is been infected. They are executed. At first the father is streched on a table and staked. Then the other family members are executed.
Cara is also brought to the Catacombs, by Mitchell as a punishment. Cara was still feeding from humans, so Mitchell knocks her two teeth out. He tells Cara that he doesn't want it but he doesn't have a choice. He needs the other vampires to accept him as the leader of them. He wants to convince them that they stop drinking blood. So he needs to punish Cara otherwise they will never accept his rules.