sometime around 1240, Arnolfo was a sculptor, and honed his craft by helping Nicola Pisano sculpt the pulpit in Siena’s cathedral. He struck out on his own, went to Rome, and garnered many commissions.
He then made his way to Florence, where his first biographer, Giorgio Vasari, asserted in 1550 that Arnolfo was the architect of Santa Maria del Fiore (aka Florence’s Duomo).
Vasari also credited him as the architect for two other monumental Florentine building projects – Santa Croce and Palazzo Signoria. Though there’s just about zero proof for these last two, it’s highly likely he was the first architect of the cathedral; and it’s 100% sure that he did sculptures for the old façade (sadly torn down in the 1580s, to be resurrected in November 2015 when the Museo dell’Opera del Duomo re-opens).
Arnolfo died sometime between 1300 and 1310.