Arecibo is the largest municipality by area in Puerto Rico, a coastal city on the island's north shore known for two very different attractions: the Cueva del Indio, a sea cave with pre-Columbian Taíno petroglyphs carved into its walls, and the former Arecibo Observatory, once the world's largest single-aperture radio telescope — now a museum after its dish collapsed in 2020.
The town itself has a long history — it was the third Spanish settlement on the island, founded in the early 17th century. The old centre around the Cathedral of St. Philip retains some colonial character, and the Paseo Víctor Rojas promenade along the rivermouth gives views over the rocky north coast. The Arecibo Lighthouse park is a popular family destination on the nearby headland.
The Río Camuy Cave Park, one of the largest cave systems in the Western Hemisphere, lies about 25 kilometres southwest — a half-day trip from the city through the impressive limestone karst interior.