U.S. Botanic Garden Washington, DC

The gorgeous U.S. Botanic Garden conservatory presents botanical variety from the desert to the tropics along a series of calm and gently meandering paths. A particular waterfall and garden display the flora of the dinosaur age. Seasonal displays include Christmas greens and poinsettias in December and January, chrysanthemums in autumn and blooming flowers at Easter. A new part of the United States Botanic Garden (USBG), the National Garden, was opened in October 2006 and includes the carefully-designed Butterfly Garden. Admission to all parts of the USBG is free.