What month and day of the year is Midsummer's Eve?

Midsummer's Eve is June 23rd- also called Saint John's Day.
The celebration of midsummer's Eve was from ancient times linked to the summer solstice. People believed that mid-summer plants had miraculous and healing power; so the plants were picked on this night. Bonfires were lit to protect against evil spirits;which were believed to roam freely when the sun turned southward again.