From the Catholic Encyclopedia:
"In the spring of 1599, the trial was begun before a commission of the Roman Inquisition, and, after the accused had been granted several terms of respite in which to retract his errors, he was finally condemned (January, 1600), handed over to the secular power (8 February), and burned at the stake in the Campo dei Fiori in Rome (17 February). Bruno was not condemned for his defence of the Copernican system of astronomy, nor for his doctrine of the plurality of inhabited worlds, but for his theological errors, among which were the following: that Christ was not God but merely an unusually skillful magician, that the Holy Ghost is the soul of the world, that the Devil will be saved, etc."
He seems rather calm amidst the flames, though.
That is a painting not a photograph.
It is nice that the Catholic Church of that day was a little less barbaric than the secular world, but it still makes one wonder how anyone claiming to be Christian could be that cruel. The bible makes it clear what they should have done with the blasphemer: kicked him out of the church and treated him with the same disdain as a pagan.