Caesarea was first built in 22 BCE by Herod, a Roman as a deep sea harbor. It use to be the largest deep sea harbor. It had tons of stores, baths, a massive roman temple, ampathearter and hippodrome which is a massive gaming area.
Over a very long period of time the harbor was destroyed by earthquakes, rebuilt, taken over and modified, destroyed again and taken over again, and then just flat out deserted after one last earthquake took out the city.
Now its been turned into a national park. It cost about $10 per person to get in during the day. There are a few restaurants and little overpriced shops. During the summer they also have diving tours where you can see ruins from the harbor.
The excavations of the baths are incredible. Marble floors were just built over so you can still see the colors and detail in most of the areas. In one part something is written in the mosaic floor. I cant read it but Im sure it says something like "No running in the baths."
Half of the theater is still standing. Its been rebuilt and still hosts shows. Maor says the top row goes for 400 shekles which is close to $150.