A tondo is a painting or a relief made in the shape of a circle. The form became fashionable in Florence in the fifteenth century, mostly for images of the Madonna, the Virgin Mary, holding the Christ Child, which wealthy families hung in their homes.
A famous example is Michelangelo's Doni Tondo, a Holy Family painted for a Florentine merchant and now in the Uffizi, the city's great museum of paintings.

The name is short for rotondo, Italian for round. English has kept both the Italian word and its Italian plural, tondi.
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Why a circle is hard to paint

In the Doni Tondo, Mary sits on the ground and twists back over her shoulder to take the Christ Child from Saint Joseph, who is behind her…
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