The Parish Church of Our Lady of O was erected when Spain was ruled by Emperor CarlosI. The First Duke of Arcos, don Rodrigo Ponce de Lyon paid for the building, finishing the interior in 1537.
In it the combination of various styles such as Gothic, Isabelline, Plateresque and Baroque are to be noted.
The church is formed with a central, unique structure in a gothic style with plateresque and renaissance tendencies together with five additional chapels.
The central strcuture is formed with three beautiful domes, separated by robust, smooth ribs.
And the dome of the great chapel is formed with intricate ribs adorned with leaves and circular rosettes where the coat of arms of the ponce de Lyon are carved together with religious motifs.