Much larger than Parque Colón [1], the Plaza de la Hispanidad is another good spot for people-watching. Located in front of the Alcázar de Colón, this very sunny plaza’s northwestern side is lined with buildings that were built in the 16th century and now have restaurants and bars in them. These establishments put their tables out on the sidewalk, making it a wonderful place to lounge with a beer at sunset, but it can be very hot during the day as there is virtually no shade.
Just down the hill, in back of the Alcázar de Colón, is the Puerto de San Diego. It was built in 1571 and was the original main gate to the city. Some remnants can still be seen of the original wall that was erected to protect Santo Domingo [2] from attackers rising from the river.
Links:
[1] http://www.moon.com/destinations/dominican-republic/santo-domingo/sights/ciudad-colonial/parque-colon
[2] http://www.moon.com/destinations/dominican-republic/santo-domingo