Siena is a city of a tremendous poetical beauty! In the sense that as you as you get inside the medieval walls it appears in its fairy-tale atmosphere with its red brick towers and buildings.
There are so many altitude gaps that the views and the glimpses are multiplied, all stunning.
A 2-3 hours guided walking tour is the minimum time to spend to have an appreciation of the highlights of Siena. Starting from the gothic church of San Domenico, one of the St. Catherine’s  favourite places to pray and very close to the neighborhood of Fontebranda where she was born, after a quick glimpse at the 16C Medici Fortress, the tour would take you in Via de’ Banchi di Sopra where one can find the most incredible and finest palaces built for the riches families of bankers with their ranting names: Tolomei, Piccolomini, Salimbeni. Passing by the 15C Loggia della Mercanzia we would finally get into the amazing Piazza del Campo, which has been since a longtime the meeting place of social and civil life of Siena. The Palazzo Pubblico, the Fonte Gaia, the Torre del Mangia (Mangia’s Tower) are the backdrop of the famous Palio horse race, held in the square twice a year in summer, where the “contrade” jockeys ride the horses bareback. This event is unique in Italy and in the world and you will be informed about every detail. We will take a break tasting the typical Sienese sweets and then we'll admire the Duomo or Cathedral, majestic from the exterior but if you wish I would be pleased to show you also the inside, full of masterpieces.
If you have more time  and would like to spend a full day on the tour, I'll be glad to accompany you to one of the city's museums, such as the St. Catherine’s House, the ancient Santa Maria della Scala Hospital with its precious frescoes and art treasures, the Opera del Duomo Museum with the famous Maestà painting by Duccio, the frescoes by Simone Martini and the Ambrogio’s Lorenzetti Good and Bad Government inside the Palazzo Pubblico and  the National Gallery of Painting with its incredible old masters works - but not before having had a delightful lunch with traditional local dishes!