Denver is currently the capital and largest city in the state of Colorado.
In Heart of Darkness, Damon and Elena came to Denver to get Jeremy. Upon arrival, they learn that Kol had been Jeremy's "friend", keeping an eye on him for Niklaus so he could be used as leverage against Bonnie into unlinking the Originals. After Kol arrives at the batting cages, he attacks Damon who manages to gain the upper hand and temporarily kill the Original.
They escape to a a motel nearby, far enough away where Kol couldn't find them and this is where Elena, Damon and Jeremy contact Rose-Marie in order to discover who was the head of her bloodline. Through her, they find out she was turned by a vampire named Mary Porter, who Damon has heard of. Damon reveals she lives in a house in Kansas. They leave the next morning.
- Damon and Elena kiss for the third time outside of the motel.