What Leonardo da Vinci painting in the Louvre features the Virgin Mary in a grotto?

What Leonardo da Vinci painting in the Louvre features the Virgin Mary in a grotto? It is The Virgin of the Rocks.

The Louvre’s Virgin of the Rocks shows the Virgin Mary, the infant Jesus, the infant John the Baptist, and an angel in a mysterious rocky landscape. Leonardo’s use of a grotto rather than a conventional architectural setting gives the painting its familiar title and creates an atmosphere of natural wonder, shadow, and discovery.

The Louvre version is generally considered the earlier of two closely related paintings by Leonardo. Most art historians date it to about 1483–1486, when Leonardo was working in Milan. The picture was painted in oils on a wooden panel and was later transferred to canvas. Its soft transitions between light and shade are a celebrated example of Leonardo’s sfumato technique.

The London version in the National Gallery is not simply a duplicate with no differences: the figures’ gestures, gazes, colours, and details of the landscape vary. The paintings are also linked to a commission for an altarpiece in Milan. A common mix-up is selecting The Annunciation, another famous Louvre work by Leonardo, but that painting presents Mary in an architectural interior rather than a grotto.