Observations on the Forum Colonnades

by James G. Cooper, Sarah Butler, and John J. Dobbins


An examination of the forum colonnades and associated stylobates leads to the conclusion that the stylobate in front of the Eumachia Building and the Sanctuary of the Genius of Augustus is a nineteenth century restoration. This reopens the question of whether or not an ancient colonnade once stood in front of the Sanctuary of the Genius of Augustus. New observations also help in reconstructing the colonnade in front of the Imperial Cult Building and understanding the relationship between the cult building's facade colonnade and the adjacent forum colonnades.

As usual, any observation regarding the buildings in the forum is attended by the realization that August Mau examined the same evidence 100 or more years ago. In an 1892 article Mau observed that "the present edge of the whole west side [of the Eumachia Building's chalcidicum] is without any doubt modern." He does not elaborate any further on the reasons for such certainty. The position of the columns are certain, however, he continues, because the preserved statue bases mark their locations. We agree with both observations and provide below an expanded discussion of the evidence for recognizing the stylobate as a modern reconstruction. While the ancient column placement can be established with relative accuracy, the varied interaxial distances within the present restoration indicate that there is some flexibility in establishing the correct placement of the columns. In addition, by adducing the evidence from the Imperial Cult Building and its connection with the Macellum colonnade, a case can be made that the forum colonnade also continued in front of the Sanctuary of the Genius of Augustus. (The sanctuary frequently called the Temple of Vespasian is here designated the Sanctuary of the Genius of Augustus). The difficult question of the date of the colonnade is not our concern in the following discussion.

Features of the Ancient Stylobates

The forum's authentically ancient stylobates establish a point of reference for the several anomalous features of the nineteenth century restoration. Ancient stylobates still in situ are found south of the Via dell'Abbondanza along the east side of the forum, along the entire southern edge of the forum, along most of the west side, and finally, in front of the Macellum. These in-situ stylobates consist of precisely cut, smoothly dressed blocks of white limestone that are carefully laid to produce level upper surfaces and straight front edges. The stylobate associated with the Porticus of Popidius at the southeastern corner of the forum is a good example (fig. 1). Visible in the illustration are the stylobate and colonnade, a broad apron of white limestone set one step below the colonnade, and the white limestone pavement of the forum one step below the apron. The pavement of the forum is therefore set two steps below the portico that defines the forum's open space. The same conditions exist along the southern margin of the forum (fig. 2) and along most of the west side. The section of the west colonnade where this pattern is interrupted can also be recognized as restoration.

Beginning at the colonnade south of the Via dell'Abbondanza and continuing counterclockwise to the northwestern corner of the forum, columns rest on lava footings. They are not set directly on the limestone stylobate. While this condition can be detected along the whole length of this section of the colonnade, the clearest evidence comes from the northwestern corner of the forum where missing columns reveal the underlying lava footings. A view from within the colonnade, looking toward the Temple of Jupiter, orients the viewer (fig. 3). Nearby is a keyhole-shaped lava footing that once supported a column (fig. 4). The limestone blocks of the stylobate are cut to surround the lava footing. An adjacent section of the colonnade shows the same situation with a column still in situ (fig. 5). As the stylobate blocks extend to the rear of the columns and their footings, the illusion is created that the columns are set on the stylobate itself.

The treatment in front of the Macellum is somewhat different, but still follows the familiar pattern of bedding the columns on lava footings (fig. 6). Here the footings are approximately square in plan. Limestone stylobate blocks fit precisely between the footings and project a few centimeters beyond them. The ends of the stylobate blocks are notched or stepped to accommodate the plinths of the Corinthian columns which overhang the footings by a few centimeters on the north and south. This arrangement is quite clear at the right of fig. 6 where the column and plinth are missing. Part of the arrangement is a facing block that masks the front (western) face of the footing and aligns with the stylobate block. The column at the left of fig. 6 with its plinth illustrate the finished condition: the footing is completely masked and the appearance is created that the marble Corinthian order is bedded directly on a stylobate of white limestone. Here, too, the stylobate extends to the rear of the plinths.

The apron that serves as an intermediary step between the forum colonnade and the pavement of the open forum is not employed in front of the Macellum or in the space to the west of the Temple of Jupiter. Instead, a shallower step effects the transition from colonnade to forum pavement. The apron begins at the southern end of the Macellum colonnade and at an analogous point to the west of the temple of Jupiter.

In summary, the hallmarks of the ancient stylobates are precision in the cutting and laying of blocks, a two-step descent to the forum that includes a broad apron as an intermediary level, columns set on lava footings, and stylobate blocks extending to the rear line of the columns and their footings.

The Restored Stylobates

In contrast to the situation just described, the stylobate in front of the Eumachia Building and the Sanctuary of the Genius of Augustus is anomalous in several ways. Many of its blocks are smaller than normal stylobate blocks and are set headerlike among larger blocks(fig. 7). The blocks themselves are laid in an irregular fashion that lacks the precision of the ancient masonry and produces an upper surface that is less regular than the forum's in-situ stylobates (fig. 8). The vertical sides that face the forum are not finely dressed. Moreover, the alignment of the blocks fails to produce a straight line along the stylobate's western face (see fig. 1 for a view from the southeastern corner of the forum). The outward curve in front of the Eumachia Building and the Sanctuary of the Genius of Augustus contrasts markedly with the straight edge of the stylobate in the foreground of fig. 1. The curvature is quite clear when viewed from a closer distance (fig. 9).

It is also clear that two blocks cut to surround the footings of a Doric column in the manner discussed above have been incorrectly incorporated into the section of stylobate in front of the Eumachia portal (fig. 10). The blocks in question are those in the center of fig. 10. For a detail of the left (north) block, see fig. 11; for a detail of the right (south) block, see fig. 12. As their curved cuttings are improperly aligned to receive a column and as the columns in front of the Eumachia Building are set on plinths, it is clear that these two blocks are not in a primary use-related context. The small pieces of broken marble veneer seen in fig. 010 are additional features of the modern reconstruction. It is likely that the two stylobate blocks derived from a disturbed and now restored section of the western colonnade. Furthermore, the relationship of the columns to the stylobate is anomalous. The columns in front of the Eumachia Building are bedded directly on the limestone stylobate rather that on tufa foundations as elsewhere along the forum colonnade (including the sections in front of the Imperial Cult Building and the Macellum), and they overhang the stylobate on the eastern side. Taken together, these observations indicate that the stylobate in front of the Eumachia Building and the Sanctuary of the Genius of Augustus is a completely modern arrangement.

Nineteenth century photographs provide a terminus ante quem for the reconstruction of the stylobate and prove that the reconstruction took place shortly after the excavation of the east side of the forum. (See Baldassare Conticello, et al, Fotografia Pompei nell'800 dalle collezioni del Museo Alinari, Florence 1990, nos. 8, 9, 33, 45; the earliest is no. 9, ca. 1862.) Ancient salvaging in this region must have been particularly vigorous and accounts for the removal of pavement, apron, stylobate, and numerous elements of the columnar order. A partially salvaged section of the forum's western stylobate must have provided the two circularly cut blocks that the restorers incorporated into the rebuilt Eumachia stylobate (figs. 4-6).

Using the evidence presented so far it is possible to offer some reconstructions of the forum's eastern colonnade. The apron can be treated most easily. As the vertical distance from the Eumachia Building's chalcidicum to the forum surface is too great for a single step, it seems reasonable to restore the apron as an intermediary level along the entire east side of the forum. This is easily achieved by connecting the preserved patch of apron at the Imperial Cult Building with the apron at the southeastern corner of the forum. Fig. 13 presents the preserved sections of apron; fig. 14 restores the apron in the area between the two preserved sections. The apron is therefore restored as a unifying element interposed between the forum porticoes and the forum pavement and extending from the front of the Temple of Jupiter around the whole forum.

A Colonnade in Front of the Sanctuary of the Genius of Augustus?

The argument that there was never a colonnade in front of the SGA presumably stems from the absence of any trace of columns on the stylobate. That is, there are no lava footings of the type seen elsewhere in the forum and there are no indications on the stylobate itself, such as setting marks or dowel holes as seen on the lava stylobate inside the Eumachia Building. Moreover, no columns that might have belonged to a colonnade in this location were recovered in the excavations. However, once it is recognized that this stretch of stylobate is not ancient, it ceases to play a role in the debate and no longer constitutes evidence for the absence of a colonnade in this area.

Apart from a prima facie likelihood that a colonnade surrounded the entire forum, there are intimations in the colonnade of the Imperial Cult Building that point to a colonnade where there is now a lacuna. As reported by Mau 100 years ago, seven of eight original tufa footings for a colonnade are still in situ in front of the Imperial Cult Building (A. Mau, "Der Staedtische Larentempel in Pompeji" RM 11 (1896) 291 and plan on 285). These are the seven southernmost footings. The northernmost footing had been robbed out and is restored on Mau's plan as a (barely) dotted square. Mau emphasizes the proximity of the footing to the southernmost footing of the Macellum's forum colonnade. He did not develop the argument any further.

The colonnade in front of the Imperial Cult Building can be reconstructed as an octastyle portico that relates directly to the cult building. The order was taller than the order of the adjacent porticoes and therefore raises the question of the manner in which the transitions were effected.


Plan A presents the Imperial Cult Building, the seven large footings in front of it, the southernmost footing associated with the Macellum's forum colonnade, the edge of the restored stylobate that extends to the south (green), and the seven columns that have been erected in front of the Eumachia Building. Although the lava footings are generally squared in plan, the inset makes it clear that they are not perfect squares. Within the inset, the footings are numbered from north to south; footing 1 is lacking.

A photograph taken from the south along the line of the Macellum's forum colonnade makes it clear that the oddly shaped footing next to the lacuna for footing 1 belongs to the Macellum colonnade (to be provided). The footing is larger than the 0.75 m. square Macellum footings and is anomalous in shape (and damaged as well). Its surface presents two separately dressed surfaces. The northern half bedded the southernmost column of the Macellum's forum colonnade. The southern half accommodated a pilaster that served as the northern termination of the the cult building's colonnade. Also clear from the plan and from photographs is that the colonnade for the Imperial Cult Building projects forward of the colonnade of the Macellum. Fig. 15 is an as-yet unfinished CAD model of the Imperial Building with tis restored colonnade and fig. 16 is a detail of the juncture of between the cult building and the adjacent Macellum colonnade (the Macellum colonnade appears in plan in yellow).


Plan B presents the next steps in the reconstruction. Footing 1 is easily restored by mirroring footing 8 around the central east-west axis of the Imperial Cult Building. The northern termination of the Imperial Cult Building's colonnade against the Macellum colonnade serves as the model for the probable southern termination. The oddly-shaped Macellum footing is mirrored in a similar fashion to locate the northernmost footing for the colonnade in front of the Sanctuary of the Genius of Augustus. (The green line at the right edge of the plan is the edge of the restored stylobate as it abuts footing 8.)


Plan C restores a colonnade in front of the Eumachia Building and the Sanctuary of the Genius of Augustus. The column spacing of the present columns in front of the Eumachia Building are uneven. From south to north, the first five interaxial distances are (in meters) 2.269, 2.323, 2.315, 2.270, 2.293. The interaxial distance used in Plan C is 2.313. This interaxial, or one close to it, would result in the placement of a column on the prepared bedding of the footing that is restored (by us in plan) on the basis of the southernmost Macellum footing.

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