You walk through the city, and as you are walking around you see a old house, at the back of the house you see a small hole that leads to a ruined room, in there you realise there is a cracked wall ready to break, if you choose to break the wall then a cave reveals itself, after some time exploring the cave you suddenly come across another ruined wall, after you destroy the wall and clear the debris, a room with a stairway appears and if you choose to descend you are suddenly into an abandoned hallway with 2 paths to take, here lies the begin of a great adventure or a gruesome death.
Dungeon Map Link, done with yEd Graph Editor: https://www.dropbox.com/s/xgu56c6e65xiazk/City%20Vampire%20Dungeon.graphml?dl=0