Cueva ventana or the window cave is a large cave situated atop a limestone cliff in arecibo puerto rico overlooking the magnificent ro grande de arecibo valley from the window cave is a breathtaking view on this tour youll take a 45 minute walk with a guide to experience this natural beauty after visiting cueva ventana the second stop is at the indian cave a coral surface cave of rocky limestone carved out through the pounding of the sea over time view petroglyphs made by the extinct