While the Duomo in Siena is truly full of interesting and beautiful things, if you've left yourself time to see only one thing of consequence then it really should be the magnificent Museo Civico in the Palazzo Pubblico (Townhall) in the Piazza del Campo. While the building itself, built between 1297 and 1305 is considered an excellent example of gothic secular architecture, it's the art within that really stirs the soul. The chief masterpiece from an artistic and political point of view is the Sala della Pace, which houses on three walls the stunning fresco of the Allegory of Good and Bad Government. It was completed between 1337-39 by Ambrogio Lorenzetti in the room where The Nine chief magistrates met to govern Siena. In addition to the iconic images of a languid Peace and a busy Justice, assisted by angels, it contains beautifully detailed images of the Renaissance city and citizens of Siena and its surrounding countryside enjoying the effects of both good and bad government (although the latter has suffered some water damage). And in a country full of attention grabbing "Madonna col Bambino e you-name-it", the huge red, blue and gold Maesta, painted in 1325 by Simone Martini, is worth contemplating with its grand canopy and nearly gender balanced legion of saints. The opposite wall in the Sala del Mappamonde has an odd collage of frescoes from different periods. The graphic black and yellow on bright blue portrait of soldier of fortune, Guidorriccio da Fogliano, and his draped horse, painted in 1329, has a modern trendy quality to it and in fact does decorate half the t-shirts in the gift shop. Below it, however, is a much faded fresco and on either side two exquisite trompe l'oeil saints in niches probably done a couple centuries later. Oddly, bisecting this large high ceilinged room on the day we visited in June was a giant swivelling white hoop--the kind of art that makes you wonder weeks later, "what was that about?" Many other pieces are much more straight forward including a room covered in frescoes of the life of Pope Alexander III, a former native of Siena. The museum ceilings are also wonderfully painted and gilded and a small dark wood chapel splendidly carved and decorated. There are several interesting pieces of sculpture too. The museum also provides access to a wide loggia on the second (third to us North Americans) floor that gives a fabulous view looking south over Siena and the surrounding area. If you can manage the long broad staircase go up and join the noisy swallows. Come down after and browse through the gift shop. It leans heavily on books on art for all ages but does have some postcards and t-shirts and little tchotchkes.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.