This is a lightly forested park on the Third Hill. The city's primary aqueduct, which originates in the hills to the east of the city, ends here after crossing the city walls. The water supplies the nympheaum - a grotto-esque temple to the nymphs of the springs that feed the aqueduct. The water is distributed from here to the many cisterns in the city through a network of mostly underground aqueducts.
The park is unplanned and retains a more-or-less natural feel, though the copses of trees show some sign of having been harvested in the past. There are some wild animals here - rabbits, snakes, etc. This should be a suitable area for low-level characters to kill things. There should also be some gatherable herbs. There should be good views of some of the harbours, the palace, and the large temple.
The nymphaeum is a grotto-esque temple with a large fountain in the center. It is mostly open to the air. It is used for weddings. There should be some number of priests here. There should also be a quest of some kind to get in good with the nymph.