This is an arial reconstruction of the Forum that shows the circular structure as well as the placement of many of its famous statues. Notice the arches on either side that lead back onto the Mese.
This reconstruction shows how the column would have been topped with a equestrian statue of Emperor Justinian as well as been covered in brass which would have shined in the light.
The column was demolished in 1719 and the base is now wedged between two buildings with a restaurant tucked behind it. But you can still get a sense of the scale.