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The Gregorian Chapel, Pope Gregory XIII's primary architectural endeavor, stands as a testament to his patronage of the arts. Commissioned in 1580 and completed in 1584, the chapel is renowned for its opulent interior, adorned with intricate frescoes by renowned artists such as Federico Zuccari and Girolamo Muziano. The chapel's design incorporates elements of both Renaissance and Mannerist styles, showcasing the artistic sensibilities of the period.