In addition to showing the facade of the Basilica Ulpia in Trajan's Forum, the Severan Forma Urbis depicts a part of the Area Fori. There, in line with the east porch on the facade of the Ulpia, a double row of dots continues the lines of the porch columns. Are these symbols columns, statues or trees? Only re-excavation of this zone could clarify this question.In early 1982, the authors undertook this work, clearing a space 6 × 25 m. which extended from the east porch of the Ulpia to the SE corner of the nineteenth century wall around the previously excavated zone. Although the disturbed soil deposits contained only modern debris, we uncovered several strata of the ancient pavement. Below the vanished marble slabs, the bedding mortar rested on caementa sustained by a stratum of rubble. At the S end of the trench appeared the most significant feature: a deep, rectangular hole. Contemporary with the construction of the Forum, it was probably a bedding pit for an ancient tree. Yet, where the Forma Urbis shows a row of dots in line with the east porch of the Basilica, we found only a single hole. We suggest, however, that, since scale and detail on the Marble Plan are only approximate, its maker abridged the distance between the columns of the east porch and the first two trees of the avenue aligned with them. Consequently, our pit probably marks the position of the first tree in the west row.