On August 15, 1843, Tivoli Gardens opened in Copenhagen.
It's the second oldest amusement park in the world; the oldest is in nearby Klampenborg. Denmark's King Christian VIII agreed to grant the charter to the park's founder, Georg Carstensen, after Carstensen pointed out that "when the people are amusing themselves, they don't think about politics." He designed it mainly as a pleasure garden, with flowers, cafés, theaters, and bandstands set in a lovely park setting.
Today, almost none of Carstensen's original park remains; in 1943, Nazi sympathizers bombed it, burning most of the buildings to the ground, but rebuilding started immediately and the park reopened just a few weeks later.
In 2009, Tivoli Gardens became the first amusement park to operate entirely on wind-generated power.
Denmark's borders are now open to visitors from most European countries and some countries outside Europe, but remain closed to tourists from many other parts of the world.
(Got most of this from today's Writer's Almanac listing, actually)