The Cathedral of Siena is one of Italy's most spectacular examples of Roman-Gothic architecture, dazzling visitors with its striped marble facade and richly decorated interior. Step inside to admire masterpieces by Donatello, Michelangelo, and Pinturicchio, alongside the extraordinary inlaid marble floor, made up of 56 mosaic panels crafted over two centuries by 40 different artists. Explore the Piccolomini Library, home to precious frescoes and illuminated manuscripts, and the Duomo Nuovo. A truly unmissable stop for art, history, and architecture lovers visiting Siena.

The Piccolomini Library, inside Siena Cathedral, is one of the city's most dazzling hidden gems. Commissioned by Cardinal Francesco Piccolomini in honor of his uncle Pope Pius II, it houses a breathtaking series of frescoes by Pinturicchio, vividly depicting scenes from the pope's eventful life. The room also displays precious illuminated manuscripts and choir books collected over centuries. With its vibrant colors and intricate detail, it's a true Renaissance treasure not to be missed.

Tucked beneath the apse of Siena Cathedral, the Baptistery of San Giovanni is a hidden gem not to be missed. Built in the 14th century, its Gothic facade leads into a richly decorated interior centered around one of the finest works of the early Renaissance: the hexagonal baptismal font. Its bronze panels were crafted by masters including Jacopo della Quercia, Donatello, and Lorenzo Ghiberti, alongside frescoes and sculptures adorning the surrounding walls and ceiling.

Climb to the top of the Facciatone, the soaring unfinished facade of the Duomo Nuovo, for one of the finest panoramic views in Siena. Begun in 1339 as an ambitious expansion of the Cathedral, the project was abandoned after the Black Death of 1348, leaving this striking facade standing on its own. A narrow spiral staircase of around 130 steps leads to a terrace overlooking Siena's terracotta rooftops, towers, and the rolling Tuscan hills beyond.

Step into the Oratory of San Bernardino, built on the spot where the Franciscan saint once preached to the people of Siena. Its upper chapel is a hidden Renaissance gem, richly frescoed with Stories of the Virgin by masters Sodoma, Beccafumi, and Girolamo del Pacchia. The adjoining Diocesan Museum showcases centuries of Sienese sacred art, offering a quieter, more intimate alternative to the city's main attractions.

Housed in the unfinished nave of the Duomo Nuovo, the Museo dell'Opera del Duomo safeguards the Cathedral's original masterpieces, saved from the elements over the centuries. Highlights include Duccio di Buoninsegna's celebrated Maestà altarpiece, Giovanni Pisano's original facade sculptures, and Duccio's stained-glass rose window. The museum also grants access to the Facciatone, Siena's finest panoramic viewpoint.