GB. USA. New York City. 1970. Four planes "flying heart" over the town. © Rene Burri/Magnum Photos

Celebrated every 14th of February, St Valentine's Day was originally known by the Romans as the festival of Lupercalia, a celebration of Juno, the Goddess of love. Cards would be drawn randomly to partner men and women together for the feast and the sexual games which were an integral part of it.
With the ascendance of Christianity, pagan festival days were replaced with rather more austere Christian versions, and in recent years the festival has become more commercialised. It has been estimated that over a billion Valentine cards are sent every year, the biggest card sending occasion apart from Christmas.