A.T. Robertson Commentary John 19:13

"When Pilate therefore heard these words, he brought Jesus out, and sat down on the judgment-seat at a place called The Pavement, but in Hebrew, Gabbatha." — John 19:13 (ASV)

Sat down on the judgement seat (εκαθισεν επ βηματος). "Took his seat upon the βημα" (the raised platform for the judge outside the palace as in Ac 7:5). The examination is over and Pilate is now ready for the final stage.

The Pavement (Λιθοστρωτον). Late compound from λιθος, stone, and the verbal adjective στρωτος form στρωννυμ, to speak, a mosaic or tesselated pavement, spread with stones, in 2 Chronicles 7:3, Josephus, Epictetus, papyri. The Chaldean name Γαββαθα, an elevation, was apparently given because of the shape.