Jaca – A guide to the historic capital of Aragón

Jaca has been inhabited since at least the 3rd century BC, but its importance grew dramatically during the Middle Ages.

In 1035 Ramiro I, the first King of Aragón, made Jaca the capital of his newly formed kingdom. The name Aragón itself comes from the River Aragón, which flows down the Canfranc Valley north of Jaca before continuing south.

Under Ramiro I and his successors, the small kingdom gradually expanded through military victories against both Muslim territories and neighbouring Christian kingdoms. As Aragón grew in power, Jaca flourished as an important political and religious centre.

During the reign of Ramiro’s son, Sancho Ramírez, the town received a royal charter in 1077 that allowed weekly markets and encouraged trade. The construction of the cathedral began during this period, and the seat of the Bishop of Aragón was moved to the city. Defensive walls were built around the town and Jaca quickly attracted new settlers and merchants.

Jaca’s time as capital ended in 1096 after the Christian reconquest of Huesca, when the royal court moved to the larger city. In the following centuries Aragón’s political centre shifted further south to Zaragoza.

The Cathedral of San Pedro de Jaca is one of the most important Romanesque monuments in Spain and is widely considered the first Romanesque cathedral built in the country.

Construction began in 1077 during the reign of Sancho Ramírez and continued into the early 12th century. Despite later alterations and restorations, the building still preserves its original Romanesque layout.

One of the cathedral’s most distinctive features is the decorative stone pattern known as the “ajedrezado jaqués” — a chessboard-like design that later spread along the Camino de Santiago as pilgrims travelled west towards Santiago de Compostela.

Inside, the cathedral follows a basilica plan with three naves. The central nave is higher than the side aisles and is separated by alternating columns and cruciform pillars topped with beautifully carved Romanesque capitals.

One particularly interesting corner of the cathedral is the Chapel of Santa Orosia, the patron saint of Jaca. According to legend, this Christian noblewoman was executed in the 8th century after refusing to marry a Muslim prince. Her story is illustrated in a series of striking paintings in the chapel.

The Citadel of Jaca

One of the most striking landmarks in the town is the Citadel of Jaca, also known as the Castle of San Pedro.

This impressive pentagonal fortress was built in the late 16th century during the reign of Philip II. It was designed to defend the northern frontier of Spain and was one of the first fortifications in the country built specifically to resist cannon fire, with thick low walls and angled bastions.

The citadel remains remarkably well preserved, complete with moat, barracks, bastions and drawbridge.

Today visitors can walk around the park surrounding the fortress, where deer now live peacefully in the moat — a curious and rather charming sight in the middle of the town.

Inside the citadel you’ll also find the Museum of Military Miniatures, which displays over 30,000 miniature figures representing historic battles and military scenes from ancient Egypt to the modern era.

The Clock Tower

Another historic landmark in the old town is the Clock Tower, also known as the Prison Tower.

Built in the mid-15th century, the four-storey Gothic tower originally served as the town prison. After the town council purchased the building in the 16th century, it was later used to house the city’s bells.

Although the tower cannot be visited inside, it stands in one of the most attractive corners of the old town. Nearby you’ll find a statue of King Ramiro I and a small square surrounded by cafés and restaurants with outdoor terraces — a lovely place to pause during a stroll through the town.

Jaca has much more to offer than its historic monuments. Throughout the year the town hosts festivals, markets and cultural events, and its lively atmosphere makes it a favourite stop for travellers heading into the Pyrenees.

Whether you’re exploring the mountains nearby or following the Camino de Santiago, Jaca is a wonderful place to slow down, enjoy some excellent food and discover a fascinating piece of Aragón’s history.