Solstitial celebrations still center upon June 24, which is no longer the longest day of the year. The difference between the Julian calendar year (365.2500 days) and the tropical year (365.2422 days) continue to move the day associated with the actual astronomical solstice forward approximately one day in approximately every seven centuries. (disputed — see talk page)

History
In the 7th century, Saint Eligius (died 659/60) warned the recently-Christianized inhabitants of Flanders against these pagan solstitial celebrations. According to the Vita by his companion Ouen, he would say:

"No Christian on the feast of Saint John or the solemnity of any other saint performs solestitia [summer solstice rites] or dancing or leaping or diabolical chants." Indeed, as Saint Eligius demonstrates, Midsummer has been Christianized as the feast of Saint John the Baptist: notably, unlike all other saints' days, this feast is celebrated on his birthday and not on the day of his martyrdom, which is separately observed as the "Decollation of John the Baptist" on August 29. That more conventional day of Saint John the Baptist is not marked by Christian churches with the emphasis one might otherwise expect of such an important saint.

As for his solsticial birthday, the Roman Catholic Church celebrates the Nativity of John the Baptist (June 24th) as a Solemnity, which is the highest degree a liturgical feast can have. It is even one of the few saint's feasts that is celebrated even when it falls on a Sunday; typically the feast of a saint is superseded when it falls on a Sunday. There is hardly any way that the feast of St John the Baptist could be given more emphasis in the litugical calendar.

The celebration of Midsummer's Eve was from ancient times linked to the summer solstice. People believed that at midsummer plants had miraculous and healing powers and they therefore picked them on this night. Bonfires were lit to protect against evil spirits which were believed to roam freely when the sun was turning southwards again. In later years, witches were also thought to be on their way to meetings with other evil powers.

In Sweden Midsummer celebration originates from the time before Christianity, it was celebrated as a sacrifice time in the sign of the fertility.

The solstice itself has remained a special moment of the annual cycle of the year since neolithic times. The concentration of the observance is not on the day as we reckon it, commencing at midnight or at dawn, but the pre-Christian beginning of the day, which falls on the previous eve. Midsummer's Eve is in Sweden and Finland considered the greatest festival of the year, comparable only with Walpurgis Night, Christmas Eve, and New Year's Eve.

Modern celebration
Midsummer or Litha is listed on the reconstructed Germanic calendar used by some Germanic Neopagans. In modern times, Litha is celebrated by Germanic Neopagans or Heathens who emphasize the reconstruction of Anglo-Saxon Germanic paganism.

Neopaganism and Wicca
Midsummer, usually referred to by the traditional name, Litha, is one of the eight solar holidays or sabbats of Neopaganism, especially Wicca. It is celebrated on the Summer Solstice or close to it. The holiday is considered the turning point at which summer reaches its height and the sun shines longest, but at the same time it is said we are reminded that the days will soon begin to shorten. Among the Neopagan sabbats, Midsummer is preceded by Beltane and followed by Lughnasadh or Lammas.