Architect Usko Nyström from Nyström-Petrelius-Penttilä Architects won the architecture competition of the new elementary school building. The construction of the building started on October 12th, 1910. It was the 100th birthday of Uno Cygnaeus’ (1810–1888), “the father of elementary school” in Finland. The new school was named after Cygnaeus, who had been an essential figure on the reform of elementary school education in the 19th century. The construction was completed in 1912.

Cygnaeus School was the biggest school in Finland at the time, and the building had unforeseen modernities; electricity and running water. The building was designed in the typical style of the time, joining classicist motives to Jugend style. In front of the building is Cygnaeus park and in the middle of it is sculptor Emil Cedercreutz’s sculpture Äestäjä from the year 1920. In the building is situated reliefs by Cedercreutz. The school building was used as a barrack and a prison during the civil war in 1918 and as a military hospital and a vocational school during World War II. The Soviet bombing of Pori damaged the building in February 1940.

Today at Cygnaeus School is a comprehensive school of 400 students from 1st to 6th graders. The English school of in Pori is also situated at Cygnaeus School.