structural:summarization, stylistic:style_transfer
Imprisonment, trial and execution, 1593–1600

During the seven years of his trial in Rome, Bruno was held in confinement, lastly in the Tower of Nona. Some important documents about the trial are lost, but others have been preserved, among them a summary of the proceedings that was rediscovered in 1940. The numerous charges against Bruno, based on some of his books as well as on witness accounts, included blasphemy, immoral conduct, and heresy in matters of dogmatic theology, and involved some of the basic doctrines of his philosophy and cosmology. Luigi Firpo speculates the charges made against Bruno by the Roman Inquisition were:

Bruno defended himself as he had in Venice, insisting that he accepted the Church's dogmatic teachings, but trying to preserve the basis of his cosmological views. In particular, he held firm to his belief in the plurality of worlds, although he was admonished to abandon it. His trial was overseen by the Inquisitor Cardinal Bellarmine, who demanded a full recantation, which Bruno eventually refused. On 20 January 1600, Pope Clement VIII declared Bruno a heretic, and the Inquisition issued a sentence of death. According to the correspondence of Gaspar Schopp of Breslau, he is said to have made a threatening gesture towards his judges and to have replied: Maiori forsan cum timore sententiam in me fertis quam ego accipiam ("Perhaps you pronounce this sentence against me with greater fear than I receive it").

He was turned over to the secular authorities. On 17 February 1600, in the Campo de' Fiori (a central Roman market square), naked, with his "tongue imprisoned because of his wicked words", he was burned alive at the stake. His ashes were thrown into the Tiber river.

All of Bruno's works were placed on the Index Librorum Prohibitorum in 1603. The inquisition cardinals who judged Giordano Bruno were Cardinal Bellarmino (Bellarmine), Cardinal Madruzzo (Madruzzi), Camillo Cardinal Borghese (later Pope Paul V), Domenico Cardinal Pinelli, Pompeio Cardinal Arrigoni, Cardinal Sfondrati, Pedro Cardinal De Deza Manuel and Cardinal Santorio (Archbishop of Santa Severina, Cardinal-Bishop of Palestrina).

The measures taken to prevent Bruno continuing to speak have resulted in his becoming a symbol for free thought and speech in present-day Rome, where an annual memorial service takes place close to the spot where he was executed.