Adam Clarke on Acts 25:23

With great pomp - Μετα πολλης φαντασιας; With much phantasy, great splendor, great parade, superb attendance or splendid retinue: in this sense the Greek word is used by the best writers. Wetstein has very justly remarked, that these children of Herod the Great made this pompous appearance in that very city where, a few years before, their father, for his Pride, was smitten of God, and eaten up by worms! How seldom do the living lay any of God's judgments to heart!

The place of hearing - A sort of audience chamber, in the palace of Festus. This was not a trial of Paul; there were no Jews present to accuse him, and he could not be tried but at Rome, as he had appealed to Caesar. These grandees wished to hear the man speak of his religion, and in his own defense, through a principle of curiosity.