The Basilica at Ardea

The basilica of Ardea is one of the oldest basilicas of the Roman world. It was probably built about 100 B.C., slightly after the basilica of Pompeii.
Its particular interest is the fact that we can see here the transition between the open stoa and the closed basilica. It lies with a long side adjacent to the forum, but instead of a closed wall, there is an open portico which gave access to the inner of the basilica. Behind a 'curtain' of closely set columns there is the plan of a normal basilica with its central nave surrounded on all four sides by a colonnade and aisles.

When we want to study this basilica in closer detail we have to knock up against the poor state of the remains and the fact that its north-west end is truncated by the modern Via Campoleone. Nevertheless it is still possible to find out some interesting details from which it is clear that in this basilica a first attempt was made to the codification of the building type as described by Vitruvius.

The inner colonnade has 4 x 9 columns. The lower diameter of the columns is 2 1/2 feet with an axial intercolumniation of 15 feet. This gives (theoretical) internal dimensions of the nave of 120 by 45 feet, measured on axes, or 117 1/2 by 42 1/2 measured between the columns. In reality the nave measures 117 1/2 by 41 1/4 feet between the columns. This nave was surrounded on three sides by aisles 16 1/4 feet wide, while at the north-west side this aisle measured 16 feet. This gives an internal length of 154 3/4 feet. Although it is difficult to tell something certain about the thickness of the walls, it is possible to deduce a thickness of 2 feet from the poor remains in the field. This gives an outer length of 158 3/4 feet which corresponds to the dogmatic principle that the external length of a basilica equals the sum of length and width of the inner nave. Indeed 117 1/2 (internal length) and 41 1/4 (internal width) equals 158 3/4 feet.
But there is more. The axial width (measure between the centers of the nave columns and the outer walls) was intended to be 18 3/4 feet. This brings the axial proportion of the basilica to 157 1/2 by 82 1/2 feet, this width being the double of the internal width of the nave (41 1/4). It is interesting to note that these measures are multiples of the column diameter (respectively 63 by 33) and of the axial intercolumniation (respectively 10,5 by 5,5).
At the south-east end a portico was added 12 feet wide. In combination with the already explained outer length of 158 3/4 this gives us a maximum length of 170 3/4 feet. Given the very poor state of conservation of these remains we can accept an intended length of 170 feet or 68 column diameters and equal to the sum total of nave length plus nave-width over the columns (122 1/2 + 47 1/2 = 170). As for the width, if we assume that the two steps along the south-west facade are part of the building, we may accept an intended width of 85 feet or 34 column diameters.

From this it is clear that this basilica was conceived with a proportion of 2 to 1.

The south-west facade, adjacent to the forum, was formed by 16 entrances 6 1/2 feet wide, separated by 15 pilasters of 3 1/2. This gives an axial width of each door of 10 feet or 4 column diameters.

This basilica had no aedes Augusti. The rectangular construction at the north-east wall was originally a cistern, later walled off from the rest of the building.

The proportions of this building correspond or come close to the proportions given by Vitruvius for the construction of a basilica. Length:width at Ardea 2:1, Vitruvius between 3:1 and 2:1; the width of the aisle is slightly greater than the prescribed 1/3 of the width of the portico, but 16 1/4 is not far away from 15 13/16 which is 1/3 of the width of the nave, over the columns.

It is clear that Vitruvius must have known these early basilicas and that his description is based on a tradition that finds its roots in this late republican examples.

BIBLIOGRAPHY

E. Wiken, La basilica di Ardea, in Bollettino dell'Associazione internazionale di studi mediterranei, 5 (1934), pp. 7-21
C.V. Walthew, A Metrological Study of the Early Roman Basilicas, Lewiston-Queenston-Lampeter, 2002

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