The Three Cities is made up of two adjacent peninsulas each about a kilometer in length: Vittoriosa and Senglea, and the area which joins the two; Cospicua.
A car is the best option for getting around as public transport doesn't actually go anywhere onto the peninsulas. If you're visiting just Vittoriosa or Senglea then just parking somewhere at the beginning of the peninsulas rather than trying to navigate the maze-like streets is the best option.
