Beit Shean National Park has probably the best-preserved ancient Roman city in Israel. It is also an impressive city, but keep in mind that during the summer it is boiling in this area. Thus, I would suggest visiting Beit Shean during Spring or Autumn and preferably not during the hottest hours of the day. Moreover, there are guided tours on-site, and I would recommend joining them. Just ask about tours when you buy tickets.
For additional info visit: https://www.israel-in-photos.com/beit-shean-national-park.html