I The Sistine Chapel was built in 1473 by Baccio Pontelli, a Florentine architect, for Pope Sixtus IV.

It is a simple barn-like chamber, 132 feet in length, 44 in breadth, and 68 in height from the pavement.

The ceiling consists of one expansive flattened vault, the central portion of which offers a large plane surface, well adapted to fresco decoration.

The building is lighted by twelve windows, six upon each side of its length.

These are placed high up, their rounded arches running parallel with the first spring of the vaulting.