Adam Clarke on Acts 10:9

On the morrow, as they went on their journey - From Joppa to Caesarea was about twelve or fifteen leagues; the messengers could not have left the house of Cornelius till about two hours before sunset; therefore, they must have traveled a part of the night, in order to arrive at Joppa the next day, towards noon. - Calmet. Cornelius sent two of his household servants, by way of respect to Peter; probably the soldier was intended for their defense, as the roads in Judea were by no means safe.

Peter went up upon the house-top to pray - It has often been remarked that the houses in Judea were builded with flat roofs, on which people walked, conversed, meditated, prayed, etc. The house-top was the place of retirement; and thither Peter went for the purpose of praying to God. In Bengal, some of the rich Hindoos have a room on the top of the house, in which they perform worship daily.