The long-hidden space adorned with delicate charcoal drawings, inside Florence’s Medici Chapel, was discovered in 1975. Luigi Navarra/Associated Press

FLORENCE, Italy — Just four at a time, visitors soon will be allowed access to a long-hidden space inside Florence’s Medici Chapel where delicate charcoal drawings sketched on the walls have been attributed by some experts to Michelangelo.

The secret room – a tiny 33-by-10 feet space – was discovered in 1975, when officials were searching for a new exit from the Medici Chapel to accommodate increasing visitors.

The museum’s then-director Paolo Dal Poggetto “firmly believed that they were by Michelangelo,’’ said the current director, Paola D’Agostino. A fierce debate ensued, and continues to this day.

“The major scholars of Michelangelo’s drawings dismissed the attributions” at the time of discovery 50 years ago, she said. “Others had a more moderate view, in the sense they tough that some could be by Michelangelo and others could be by followers. So the debate is ongoing.”

The room was used to store coal until 1955, and then sealed closed and forgotten for decades below a trapdoor that was in turn hidden beneath furniture. The drawings themselves were discovered under two layers of plaster.

According to Dal Poggetto’s theory, Michelangelo hid in the tiny space from “the wrath of Pope Clement VII” for supporting a short-lived republic that overthrew the Medicis, sketching studies for some of his projects. They include sketches believed to be the legs of Giuliano de’ Medici, as included in the New Sacristy near the secret room’s entrance.

For most of the last 50 years, access to the room has been restricted.

Officials decided to open the room to the public on a limited basis, and will alternate exposure to LED lights with extended periods of darkness to protect the works.

Starting Nov. 15, up to 100 visitors will be granted access each week by reservation, four at a time, spending a maximum of 15 minutes inside the space.