The famous red dome, which sits 180 feet above the floor of the duomo and spans a distance of 140 feet, can be seen for miles around and is synonymous with the city of Florence itself. The church on which the dome sits is the fourth largest in Europe and the views from it must be spectacular. During its construction it was doubted whether such an engineering project could be accomplished, but it employs an ingenious herring-bone system that was revolutionary for its time. It was partly inspired by Roman building techniques, which Brunelleschi had studied along with his friend Donatello in Rome. Filippo Brunelleschi, a dominant figure in the early 15th century, is credited with introducing the principles of perspective into art.