The leading bridge
One of very good working composition rules is leading lines. That means that you should have lines in your photo, which lead to the main subject. And I think the Charles bridge in this photo works very nicely as a leading line. It just draws your eyes towards the Prague castle in the distance.
I haven’t taken many portrait oriented shots lately. They can give you a great view of a subject, but they are just not fit onto a horizontally oriented screen. But from time to time they are fine :)
