Midsummer
Sankt Hans or Saint Johns Eve is, as many other Danish traditions a mixture of pagan and Christian traditions. Sankt Hans Aften celebrates the birth of St. John the Baptist with the Danish name Sankt Hans, who is believed to have been born on June 24th. However, because Danes, according to Nordic tradition, like to celebrate the night before, Sankt Hans Aften is celebrated on the eve of June 23th – just like Christmas is celebrated on December 24th instead of the 25th. This is however not the reason for why the evening originally was celebrated. Originally, it was a pagan marking of sun solstice, which later was altered to be a Christian tradition.
In the days leading up to Sankt Hans Aften, big bonfires get build which are burned on the eve, while groups of people watch and sing songs throughout the night. For many people, Sankt Hans Eve is the night to celebrate summer while being in the company of friends and family. The bonfire would traditionally have featured a straw witch, but it is no longer a staple of the night, since it does stem from the time of persecutions of witches, that took place all over Europe in the 17th century.
You can read more about Midsummer in Denmark here.