At that time inhabitants, which were composed of strangers from different parts of the island, were united and wanted to call the town Unisan, a corruption of the words union and unidos for the sake of euphony.

During the latter part of the 19th century, legends said that the real founder of the town was a Malayan queen called of Ladya.

[citation needed] It is believed that the founding occurred in the Middle Ages when immigration of the Malayans to this country was still predominant.

This proven by the fact that no traces of Mohamed's Creed were found in that part of the Philippines when the Europeans arrived.

At the same time, it was renamed to Unisan which was derived from the Latin word uni-sancti, meaning "holy saint".

It is bounded to the north by Atimonan, to the south by the Tayabas Bay, to the west by Agdangan, and to the east by Gumaca and Pitogo.

[8] The town center (poblacion) consists of 4 barangays, R. Soliman, Ramon Magsaysay, Lapu-lapu and F. de Jesus.

The Unisan Central Elementary School is on the southeastern side of the church, while the Government Center is located at the back of the school which consists of Municipal Hall, Municipal Library, Fire Station, Police Station, Comelec Building and the Association of Barangay Captains (ABC) building.

The Tamesis Park, named after a prominent Unisanin, Florencio Tamesis, the first Filipino director of the Bureau of Forestry and considered by experts as the father of Philippine Forestry, is likewise located at the center of the town, just across the Church Basketball Court.

Friar Diego de la Magdalena, a member of the 6th Mission that arrived in the Philippines in 1594, also administered Calilayan.

The survivors took refuge near the Palsabangon River, where the missionaries, among whom was Friar Pedro de san Buenaventura, built a church, a convent and school buildings with bamboo and nipa.

In 1913, because of the crocodiles, the people relocated to the sitio of Cabuyao, where Friar de Mérida built a church and a convent with wood and school buildings with bamboo and nipa.

Marcos Tolentino, a secular priest, who In 1945, during the World War II, the church was partially destroyed; it was reconstructed by the Philippine Historical Commission in 1966.

Established in 1962 by Father Ruben Profugo (later Bishop of the Diocese of Lucena), the Parokya ni San Roque was formerly a small church attached to the Parish of St. Peter in the town proper and served by the priest/chaplains of the Holy Child Jesus Institute (Dominican Academy).

Francisco Deveza De Jesus (whom Barangay F. De Jesus was named after), Dr. Teodorico V. Valerio, Dionisio V. Valerio, and Eulogio Fernandez Several Mayors in the same era were surnamed Constantino and Isaac, two prominent names in the municipality Unisan belongs to the Quezon's 3rd district since 1987.

The festival is highlighted by a street dancing competition participated by the residents of different barangays, as well as by elementary and high school students.