The Colònia Güell Crypt is the lower part of what was going to be the church at the Colònia Güell. Colònies were small housing developments for workers, built around factories in the 19th and early 20th century Catalonia.
The Colònia Güell church was the first project in which Gaudí began to experiment with ruled surface geometry, which he later used in the project for the Basilica of the Sagrada Família. Only the church crypt was built. All its features have structural and symbolic functionality, the same as the Sagrada Familia, avoiding superfluous decorative features.
The water-drop shape of the windows helps to divert rainwater outwards and also symbolizes holy water.