As Peter Webb notes in his excellent The Erotic Arts, eroticism is rare in the art of the Early Christian period and the Middle Ages. Pagan monuments were often overtly sexual, but Christian art shunned the world of physical love. Christianity was a non-sexual religion (Virgin birth of Jesus, Saint Paul advocating clerical celibacy).
Mooning gargoyle, Frieburg, GER, photographed by macg.stiegler on 4/9/2004.
It was an era of sexual repression, but there are exceptions of course. There were elegiac comedies such as Lidia, erotic folklore such as the fabliaux, seductive enchantresses such as the Morgan le Fay, succubi and incubi, sexual church gargoyle ornamentations and Sheela na Gigs and sexual misericords.
The mooning gargoyle of Frieberg is Icon of Erotic Art #46.