The solstices are now important in Hinduism, they are supposed to divide the year (In Uttarayana, beginning Winter solstice; and Dakshinayana, beginning summer solstice). But in the Aryan times the equinoxes divided the year (in Devayana, beginning vernal equinox; and Pitriyana beginning autumnal equinox). Here is the sky chart in April 9, 2,000 BC at Arkeim, Chelyabinsk Oblast, Russia. Arkaim is an archaeological site situated in the Southern Urals steppe. For some interesting images kindly see http://www.religiousforums.com/threads/vernal-equinox-on-april-9-2000-bc.187381/
Midsummer is often celebrated on 24 June because that was when the solstice fell in Julius Caesar's calendar. When the Gregorian calendar was introduced, it put the spring equinox back to 21 March rather than 24 March because that's what had been used in the definition of Easter in the 4th century.
Neopagans, like Wiccans and Druids, celebrate the solstice as a major festival. It's not often one in traditional paganism, although I'll celebrate it as a festival in honour of Helios.