Lets look at a series of representations from the mid 19th century of the Capitoline end of the Roman Forum.

This is from a series by Alfred Nicholas Normand from 1850-1852. The top illustration shows the area at his time, with the Tabularium in the background, and, from left to right, the ruins of the temples of Saturn and the Deified Vespasian, the columns of Phocas, the base of the temple of Concord and the Arch of Septimius Severus.

The bottom illustration is his reconstruction/imagining of the same, but with the addition of a cut-away of the Basilica Julia, the Arch of Tiberius, the Golden Milestone, the Rostra and the Arch of Septimius Severus, with the temple of Concord behind it.