Best stops on walking tour

Hoping for some quick feedback. We leave on Friday on Valor. We are only in Puerto Rico from 7:00-2:00. Will probably not get off the ship till closer to 9:00. We have been to both forts, the capital building, and the cemetery. Dont feel a need to revisit any of them. Since we have 4 port days in a row, would like to make this one non-strenuous. Can anyone suggest a few other highlights to walk to via the trolley? I have the city/trolley map but dont want to walk the whole thing really. Oh and it is just me and my 13 year old son. Thanks in advance!