The cathedral has a generally Romanesque structure, although several elements are in Gothic, Renaissance and Baroque styles.
The plan is in the forms of a nave and two aisles, with three apses and two external portals, both provided with loggias (one of which in Renaissance style).
Only one of the current apses is original.
Of the other two, the central one was renovated in the 18th century, and the other one rebuilt in the same age.

The nave and the aisles are separated by arcades supported by piers which are alternatively cruciform and cylindrical in plan, an element inspired by contemporary French structures.
The capitals of the piers, in Corinthian style, have decorative motifs with vegetables and geometrical shapes.
The ceiling was originally in wood: in modern times it was replaced by cross vaults.
The large dome at the crossing is octagonal.
On the four sides are several chapels built from the late-15th century to the mid-17th century.
The earlier ones (those dedicated to the Holy Cross and to St. Augustine) are late Gothic in style, those designed in the 16th century (St. Michael and St. Jerome, for example) show late Renaissance and Mannerist influences; the chapel of St. Horosia, completely remade in the 18th century, is in Baroque style.

Artworks in the interior include the altarpiece of the St. Michael Chapel, sculpted by Gil Morales the Younger, Gabriel Yoli, Juan de Salas and the Florentine Giovanni de Moreto (or Moretto).
The latter also directed the construction of the Chapel, which is considered amongst the finest examples of the Renaissance-Plateresque architecture in Aragon.
 The altarpiece of the high altar was finished in the early 17th century.
The decoration of the central apse was painted by Manuel Bayeu, brother-in-law of Francisco Goya, in 1792-1793.
The cathedral has a generally Romanesque structure, although several elements are in Gothic, Renaissance and Baroque styles. The plan is in the forms of a nave and two aisles, with three apses and two external portals, both provided with loggias (one of which in Renaissance style). Only one of the current apses is original. Of the other two, the central one was renovated in the 18th century, and the other one rebuilt in the same age.
The nave and the aisles are separated by arcades supported by piers which are alternatively cruciform and cylindrical in plan, an element inspired by contemporary French structures. The capitals of the piers, in Corinthian style, have decorative motifs with vegetables and geometrical shapes. The ceiling was originally in wood: in modern times it was replaced by cross vaults. The large dome at the crossing is octagonal. On the four sides are several chapels built from the late-15th century to the mid-17th century. The earlier ones (those dedicated to the Holy Cross and to St. Augustine) are late Gothic in style, those designed in the 16th century (St. Michael and St. Jerome, for example) show late Renaissance and Mannerist influences; the chapel of St. Horosia, completely remade in the 18th century, is in Baroque style.
Artworks in the interior include the altarpiece of the St. Michael Chapel, sculpted by Gil Morales the Younger, Gabriel Yoli, Juan de Salas and the Florentine Giovanni de Moreto (or Moretto). The latter also directed the construction of the Chapel, which is considered amongst the finest examples of the Renaissance-Plateresque architecture in Aragon.  The altarpiece of the high altar was finished in the early 17th century. The decoration of the central apse was painted by Manuel Bayeu, brother-in-law of Francisco Goya, in 1792-1793.
Jaca Cathedral