A.T. Robertson Commentary Mark 15:16

"And the soldiers led him away within the court, which is the Praetorium; and they call together the whole band." — Mark 15:16 (ASV)

The Praetorium (πραιτωριον). In Mt 27:27 this same word is translated "palace." That is its meaning here also, the palace in which the Roman provincial governor resided. In Php 1:13 it means the Praetorian Guard in Rome. Mark mentions here "the court" (της αυλης) inside of the palace into which the people passed from the street through the vestibule. See further on Matthew about the "band."