Puerto Rico is a commonwealth of the United States, so it combines the best of a tropical island with Latin culture with the benefits of being a domestic vacation destination for American visitors. Towns along Puerto Rico's coast are popular ports of call for cruise ships. English is spoken everywhere and the US dollar is the local currency. Yet it is hard not to think that you've arrived in a Spanish colony ? few other places in the Caribbean have preserved the past so well.
Arecibo is one of the largest cities on the island and has over 500 years of colonial history especially evident in its architecture. But it's also in the forefront of technology - the Arecibo Observatory houses the world's largest radio telescope, and was featured prominently in the James Bond movie, Goldeneye.
A highlight of a tour of Old San Juan is the fortress of San Felipe del Morro, a 16th century citadel built to protect the town from attack from the sea. You get splendid views of the town from one side and the blue Caribbean Sea from the other. In the original main square of San Juan, Palaza de Armas, you'll find the Alcadia, the city hall built to replicate City Hall in Madrid, with towers, balconies and courtyards as if to remind colonial settlers of their homeland.
On the east coast, Fajardo is popular for boating and diving and nearby Playa Luquillo is one of the prettiest beaches of Puerto Rico. To the south, the city of Ponce is historically important - as a port and a focus of trade. On the western coast, the town of Rincón is popular with surfers. Offshore, the islands of Mona and Monito, located between Puerto Rico main island and the Dominican Republic, have been declared a nature reserve and form the habitat of endangered sea turtles, sea birds and marine mammals.