Click on the images to enlarge them:
There images offer five different views and representations of the port of Havana:
1. 
2. 
Above is a rendering demonstrating the shape of the bay and port itself, showing how the peninsula on the right is used as the location for the fortress. The strait is called the Canal de Estrada
2. 
Above is a rendering of San Salvador de la Punta, which in photo 2 would be on the peninsula on the left of the Canal de Estrada, on the very tip.
3. 
Above is a view facing North, from inside the port, of the fortress. In the upper right quadrant of the painting is the Canal de Estrada, and the point the peninsula in the background is San Salvador de la Punta
4. 
Above is a modern-day photo of San Salvador de la Punta
The video shown in this link, until approximately 3:00, shows the locations of the fortress: