Originally built by the WPA in 1934, the Key West Aquarium was the world's first open-air aquarium. Today Key West's oldest attraction is enclosed for all weather viewing. This family-friendly spot includes a touch tank for the kids, glassed in display tanks and a feeding tank where you can watch sharks, barracudas, tarpon, stingrays and turtles stuff themselves. The guided tours are free with admission and your ticket is good for two consecutive days.