San Juan also known for The globe’s hottest party spots cater to all tastes—glitzy, gritty, seductive, and strange Nightlife Cities in the world. San Juan is the capital and most populous city in Puerto Rico. Founded in 1521 by Juan Ponce de León, who named it City of Puerto Rico (Rich Port). The capital of Puerto Rico is the oldest city under U.S. jurisdiction, but some people argue than St. Augustine, Florida, founded in 1565 is the oldest city in the continental United States.The history of San Juan begins a long time before its official foundation, in 1493, during his second voyage, Christopher Columbus landed in Puerto Rico. He named the island “San Juan Bautista”, in honor of John the Baptist. But was not until 1508, that the Spanish government appointed Juan Ponce de León as the first governor of the island. He founded the original settlement in Caparra, now known as Pueblo Viejo, behind the almost land-locked harbor just to the west of the present metropolitan area and the city quickly became Spain’s most important military outpost in the Caribbean.