Basilica di San Petronio is a significant church located in Bologna, Italy, renowned for its splendid Gothic architecture. It dominates Piazza Maggiore and is considered one of the largest churches in the world. Named after Bologna's patron saint, San Petronio, its construction began in 1390 under architect Antonio di Vincenzo's design but remained incomplete due to a series of interruptions. The façade remains unfinished, showcasing the brickwork with marble adornments only on the lower section. Inside, the vast interior impresses visitors with its 22 chapels, beautiful frescoes, and detailed art pieces, including the 15th-century fresco series by Giovanni da Modena. One remarkable feature is the Meridian line, a sundial created by astronomer Giovanni Domenico Cassini in 1655, which is the longest indoor meridian line in the world. Despite its unfinished state, Basilica di San Petronio is a symbol of Bologna's historical and cultural significance, attracting tourists and devotees alike.