A Chequer-Board of Nights and Days

A long-missing Michelangelo sketch for the dome of St. Peter's Basilica, possibly his last design before his death, has been discovered in the basilica's offices, the Vatican newspaper said Thursday.

The sketch, drawn in blood-red chalk for stonecutters who were working on the construction of the basilica, was done by the Renaissance master in the spring of 1563, less than a year before his death, L'Osservatore Romano reported.

"The sureness in his stroke, the expert hand used to making decisions in front of unfinished stone, leave little doubt, the sketch is Michelangelo's," the newspaper wrote about the discovery, which it said will be presented at a news conference at the Vatican on Monday.

The sketch shows that Michelangelo "on the threshold of 90 years of age, even though he wasn't coming regularly to the (basilica) construction site, continued to take binding decisions" on how the work was being carried out, the Holy See's official newspaper commented.

The sketch "now becomes the last known design of the artist," the newspaper said.

Michelangelo, who began working on the basilica's construction in was in his late 80s when he did the sketch. The sketch is especially rare, the Vatican newspaper noted, because the artist ordered many of his designs destroyed when he was an old man.

The sketch was discovered in the Fabbrica of St. Peter's, which contains the basilica's offices.