Palazzo Piccolomini site features

The palace occupies the west side of Pienza's trapezoidal Piazza Pio II, with the Duomo at the centre of the square and the bishop's palace opposite. It sits at an angle of about seventy-five degrees to the rest — not carelessness but a condition of the design, so that it would stay parallel to the church of San Francesco and in line with the main street.

From the square it reads as a cube: a square plan on three floors, built of rustic light stone, with no tower, no battlement and no projection. The whole composition is in the windows. On the first and second floors two rows of large openings of equal size, evenly spaced, are set between pilasters; each window is divided into two lights by a single thin column. A frame runs below the windows, carrying along the corners and marking the floor levels inside, and between some of the windows are the family crests in stone, with the apostolic insignia in gold and silver — the only colour and the only glitter on an otherwise grey-gold front.

That regularity is the point. Where a medieval palace asserted itself by height and irregularity, this one asserts itself by repetition.

Through the main door on the ground floor you come into the central courtyard, which is rectangular and carries a loggia on stone columns. It is worth pausing on its scale: the whole of Piazza Pio II outside is, the sources note, no longer than this courtyard. Standing in one and then the other is the quickest way to grasp how small the site Rossellino was composing actually was.

The museum rooms run above — the hall of arms, Pius II's study, the bedchambers, and his art and sculpture collection.

Then the building turns round. At the back, away from the square, are the garden and the loggia that opens onto it, and the ground falls away beyond. On a clear day you look out over the Val d'Orcia to the hills of Monte Amiata. The front of the palace faces a designed square; the back faces a designed view.

• The window composition (from 1459) — two rows of equally sized, evenly spaced openings on the first and second floors, set between pilasters, each divided into two lights by one thin column: the building's entire argument, made by repetition rather than by height.
• The stone crests with apostolic insignia in gold and silver — set between some of the windows, and the only ornament of any richness on the facade.
• The square three-storey plan in rustic light stone — no tower, no battlements, nothing projecting; a cube on a medieval street.
• The rectangular courtyard with its stone-columned loggia — and the fact that Piazza Pio II outside is no longer than it, which tells you everything about Rossellino's problem.
• Pius II's study — the working room of the pope who had the town rebuilt and renamed after himself.
• The hall of arms and the bedchambers — the residential sequence, kept as a museum.
• Pius II's art and sculpture collection — assembled by him and still in the building.
• The rear loggia and the Renaissance garden — included in the guided visit, and the one place in Pienza where a framed view and a designed interior meet.
• The view to Monte Amiata — on a clear day, across the Val d'Orcia, inscribed by UNESCO in 2004 partly for having been painted so often.
• The 75-degree siting — the palace had to be set at that angle to stay parallel to the church of San Francesco and in line with the street, which is why the square is a trapezoid.