Santo Domingo is the oldest colonial city in the Americas, as well as being the capitol of the Dominican Republic. It is also the largest city in the Dominican Republic by far. Santo Domingo has a somewhat bad reputation among travelers and is often described as dangerous. At least in the old colonial zone of the city where most of the interesting sights are located, I would not consider this to be a dangerous place to be, at least in the daytime. This section of the city has almost every "first" of the new world. The first cathedral, the first brick building, the first hospital, the first collage, etc. You get the idea. For history buffs, it is a city not to miss. Even if you aren't into history, it is still worth visiting if you can drag yourself away from the beach for a day.