Arecibo was the third Spanish settlement. Visitors are drawn to the city's eucalyptus, teak and mahoe trees, which can be found in the Cambalache Forest Reserve. Arecibo is home to one of the world's most powerful astronomical observatories the Arecibo Observatory. The world's largest radio telescope's is here. It has a diameter of 1000 feet and can receive signals from up to 1000 light-years away! (GETTY IMAGES)