The "P", Protected area in San Luis Obispo, California.

The "P" is a 50-by-30-foot letter built into a hillside northwest of the Cal Poly San Luis Obispo campus. The concrete block, completed in 1957, is painted white and stands 40 feet tall and 30 feet wide, larger than the whitewashed stone and barn-door versions that preceded it.

The hillside letter dates to at least 1919, when Polygram reported students converting stone "H" marks left by San Luis Obispo High School into "P"s. Early versions were whitewashed stones, then whitewashed barn doors that rivals burned. The Block "P" club built a concrete letter 40 feet tall and 30 feet wide; after it fell into disrepair, Delta Sigma Phi and agricultural engineering students finished the present "P" on May 3, 1957.

The letter's name comes from "Poly," the school's nickname. Since 1994 the Mustang Maniacs have painted it about three times a year; clubs may repaint it only with the group's permission and must restore the standard white. Earlier, the Rally Club lit it before football games and swapped the P for a V after a win.

The "P" sits on a hill northwest of the Cal Poly campus, reached by a trail the Rally Club once carried a generator up. The letter is repainted about three times a year by the Mustang Maniacs; clubs may paint it only with their permission and must restore the standard white afterwards.

The "P" was deliberately sited so it could be seen from three places: the administration building's porch, the newly built Highway 101, and from the air, as flying was gaining popularity. A 1919 Polygram account says students first found stone "H"s on the surrounding hills and swapped them for "P"s.