San Juan, Puerto Rico is one of the largest and finest natural harbors in the Caribbean and is the second oldest city in the Americas. San Juan is center of Caribbean shipping and is the 2nd largest seaport in the area (after New York City). The Old San Juan area has streets which are paved with cobbles of adoquine, a blue stone cast from furnace slag; which were brought over as ballast on Spanish ships and time and moisture have lent them their characteristic color. The Old San Juan attracts many tourists, who also enjoy the gambling casinos, superior beaches, and tropical climate. More tourists visit San Juan each year than any other spot in the Caribbean. The cobblestone streets, interior patios, hanging balconies, plazas, historical buildings, forts, and chapels make of this remarkable city a charming and picturesque place to visit. If you stroll down the streets, you will find many interesting shops, bars, places to eat, and hidden squares. The churches are generally to be found on plazas and many have rainbow hued stain glass windows. After a long walk in old town you could go for a cooling swim. The beautiful white-sand beaches are as attractive as the sites of the town and have all the customary water sports with the expected tropical climate of the Caribbean.