Piazza Jacopo della Quercia, Public square in central Siena, Italy.

Piazza Jacopo della Quercia is the right-hand side of the parvis of Siena Cathedral, given an L-shape by the Palazzo Reale opposite the cathedral's right flank and closed to the south by the Facciatone. Its paving marks the positions of the piers planned for the never-built nave of the Duomo Nuovo, abandoned in 1357.

The square owes its present form to the abandonment of the Duomo Nuovo nave in 1357; the positions of the planned pillars remain marked in the paving. It is named after Jacopo della Quercia, the Sienese sculptor of the Fonte Gaia, whose name was given to this side of the cathedral parvis. The L-shaped space is closed to the south by the Facciatone.

The paving marks the positions of the pillars planned for the never-built nave of the Duomo Nuovo, abandoned in 1357; visitors can look for these outlines in the stone. The square is named after the Sienese sculptor Jacopo della Quercia, author of the Fonte Gaia.

The square is the right-hand side of the cathedral parvis, reached from Piazza del Duomo; the paving marks where the pillars of the unfinished nave were planned. The Facciatone closes its southern branch, so the L-shaped space is a natural stop before or after visiting the Duomo.

The paving of the square marks the positions of the pillars planned for the never-built nave of the Duomo Nuovo, abandoned in 1357. Look down to see where Siena's unfinished cathedral expansion would have stood.