Complutum

Complutum was an important Roman city situated within the bounds of the present-day municipality of Alcalá de Henares in central Spain. Portions of the ancient settlement have been excavated and are accessible at the Complutum archaeological site, located south-west of the medieval centre. The remains illustrate the development of an urban community that prospered from the early imperial period until late antiquity, displaying characteristic features of Roman civic planning, domestic architecture, religious life and public administration.

Early settlement and Roman foundation

The area of Complutum had been occupied well before the Roman period. In the 3rd and 2nd centuries BC it was inhabited by the Carpetani, a Celtiberian tribe whose fortified oppidum stood atop the Viso Hill on the opposite bank of the River Henares. This defensible position controlled communication routes and fertile meadows within the valley.
Following the Roman conquest in the 1st century BC, an initial attempt to establish a Roman-style town on the earlier site was unsuccessful. Shortly afterwards the inhabitants began the construction of a new city on the fertile plain of the Henares. The project unfolded in two phases: the first during the reign of Augustus and the second under Claudius around AD 50. In AD 74 the emperor Vespasian granted the settlement the legal rank of municipium, integrating it more firmly into the administrative organisation of Roman Hispania.
Complutum became the principal urban centre of a wide territory encompassing much of what is now Madrid and Guadalajara. Despite the stresses experienced by the empire during the 3rd century, the city expanded and received significant architectural enhancements. The period also witnessed the martyrdom of two young brothers, Justus and Pastor, during the Diocletianic persecution. Their veneration persisted and they remain the patron saints of Alcalá.
During the era of the Visigothic Kingdom, Complutum remained linked to important north-south routes that connected the Mediterranean with Gaul. The long-term preservation of the site, however, was hampered by the lack of archaeological regulation in the 19th century, resulting in the dispersal of many artefacts. Urban development in the 1970s caused major destruction, though legislative reforms in the 1980s enabled systematic archaeological campaigns and improved protection.

Urban layout and street network

Excavation and survey work have clarified the limits and internal plan of the Roman city. Complutum was built according to an orthogonal grid influenced by the ideas of Hippodamus of Miletus, as was customary in Roman urbanism from the late Republic onward. Two principal sectors have been identified: an earlier eastern zone from the 20s–30s AD with rectangular insulae of approximately 32 × 42 metres, and a western zone from the 60s AD with a more regular pattern of square insulae of 32 × 32 metres.
Around 15 decumani and 16 cardines structured the settlement, which covered nearly 48 hectares and may have accommodated between 10,000 and 15,000 inhabitants at its peak. The two main axes, the cardo maximus and the decumanus maximus, intersected at the location of the forum. The latter was the principal thoroughfare as it formed part of the major route linking Augusta Emerita and Toledo with Caesaraugusta. At the western gate a fountain dedicated to nymphs and Diana, known today as the Fuente del Juncal, marked the entry. A similar spring at the southern end of the cardo maximus served a small river port on the Henares.

The forum and public buildings

The monumental forum complex visible today dates largely to the 3rd century, when an ambitious rebuilding project upgraded earlier structures from the 1st century. A grand façade resembling a theatre backdrop was erected, clad in marble and decorated with sculptures. Its central opening bore an epigraphic poem derived from Virgil’s Aeneid, celebrating the renovation of the civic heart of the city.
Beneath the new façade a cryptoporticus was constructed, raising the ground level and creating an imposing entrance to the curia. In order to accommodate this structure, the east wing of the earlier quadriporticus adjacent to the baths was dismantled. The cryptoporticus lay above an aqueduct that had supplied the north baths, which were consequently repurposed.
The basilica, originally built in the 1st century, was entirely remodelled in the 3rd century. It functioned as the venue for judicial proceedings and commercial transactions. The building had a central nave flanked by aisles separated by a colonnade. The former north baths occupied a position beside this basilica; their heated caldarium was equipped with a hypocaust fed by two furnaces. Later, the conversion of this bath complex into the curia preserved the heating system to warm the meeting space of the local senate. The so-called Paredón del Milagro—a wall associated by later Christian tradition with the martyrdom of Justus and Pastor—belonged to this structure and long remained an object of veneration.
The southern baths, built to replace the earlier complex, reflected a more compact provincial design. Arranged in linear sequence, they comprised an apodyterium, a frigidarium, a tepidarium, and a caldarium, with hypocaust heating maintained for the warmer rooms.

Religious architecture: the auguraculum

Adjacent to the forum lay the distinctive auguraculum, the meeting place of the college of augurs. This priestly body supervised acts of divination and purification integral to public religious life. The main hall contained offering wells and six small sacrificial basins, each preserving ceramic vessels and animal remains—chiefly chickens. A separate room held another basin containing a buried child, together with small instruments and a statuette of Mercury, suggesting ritual functions connected with protection and commerce.

Domestic architecture: the House of the Griffins

In the centre of the city stood the House of the Griffins, one of the best-appointed residences in Complutum. Constructed in the mid-1st century and inhabited until its destruction by fire in the 4th century, it covered around 900 square metres. A large peristyled courtyard of roughly 99 square metres provided access to numerous rooms. Noteworthy amenities included a fireplace—unusual in Roman Hispania—and an elaborate water system.
The interior was extensively decorated with wall paintings of various styles. In the tablinum, panels of the Second Pompeian Style presented illusionistic architectural schemes framed by Ionic columns. Other rooms contained imagery of plants, vessels, mythological figures and, notably, griffins, from which the house takes its modern name. Painted imitations of wooden latticework and metal gates adorned the peristyle.

The House of Hippolytus

Despite its title, the House of Hippolytus served as the headquarters of the collegium iuvenum, a youth association concerned with social and leisure activities. The complex featured several rooms designed for recreation, the largest of which held a striking mosaic depicting a fishing scene. This work is signed by Hippolytus, a mosaicist thought to be of North African origin, perhaps from the region of modern Tunisia. The commission was likely intended for one of the city’s leading families, attesting to the cultural and economic vitality of Complutum in the high imperial period.