Unquestionably one of Italy's finest Gothic churches, Siena's cathedral (Duomo di Siena) is equally stunning inside and out, featuring the work of Italy's finest artists of the day: Nicola and Giovanni Pisano, Donatello, Pinturicchio, Lorenzo Ghiberti, and Bernini. The cathedral in its present form was begun in 1229, and the dome was completed in 1264. Around 1317, the choir was extended over the baptistery, and only about 20 years later, the people of Siena planned a gigantic expansion, which would have made it the largest Gothic building in Italy. The existing church was to become the transept of a new church more than 100 meters long, with its new nave turned by 90 degrees. These grandiose plans came to nothing when it was discovered that the foundations couldn't handle the added weight, and because the plague struck down so much of Siena's population in 1348.