National Aquarium

Aquarium in Baltimore
Image by Education Images / UIG via Getty Images

Standing seven stories high and capped by a glass pyramid, this is widely considered to be America's best aquarium, with almost 20,000 creatures from more than 700 species, a rooftop rainforest, a multistory shark tank and a vast re-creation of an Indo-Pacific reef that is home to blacktip reef sharks, a green sea turtle and stingrays. There's also a reconstruction of the Umbrawarra Gorge in Australia's Northern Territory, complete with 35ft waterfall, rocky cliffs and free-roaming birds and lizards.

The largest exhibit contains seven bottlenose dolphins kept in captivity, though at time of writing the aquarium was planning to retire them to an oceanside sanctuary by 2021 (freeing them to the wild is not an option, since they lack survival skills). These dolphins no longer perform in shows. Kids will love the 4-D Immersion Theater (admission costs an additional $5), and there are loads of unique, behind-the-scenes tours, as well as aquarium sleepovers. Go on weekdays (right at opening time) to beat the crowds.