A double stone-alley, quite good preserved, is the last remains of prehistoric population on Saint Pol site.
Several vestiges demonstrate a roman military presence in the 3rd century. Based on ancient writings, Saint Pol would have then been enclosed by extraordinary high motted walls.
As of the 6th century, the monastry site became an episcopate named "Kastell Paol". The city then extended beyond its walls.
In the 15th century, Saint Pol de Léon is a famous spiritual and cultural centre. The Pempoul harbour is at its rise. Fortified doors protected the 2000 inhabitants until the 18th century.
During the 18h century, the bishops of Léon strongly influenced the architectural style of the city. A new episcopal house was erected in 1706 and extended in 1750.
The seminary dates from 1708, the catholic college from 1788.
During the Révolution the city lost the episcopate, a rich chapter, a college, 3 religious communities, a retirement house and 15 religious houses. Then started 100 years of economical decline. "Today Saint Pol de Léon is a dead city" was Flaubert report in 1847.
19th and 20th centuries
As of 1883, the railway contributed to the considerable expansion of the agricultural production. In 1890 Saint Pol de Léon became the main commercial centre in France for vegetable exportation.
Nowadays, the region is still the strongest concentration for horticultural production and transformation.