Pergamum

From the modern city of Bergama, we entered the site of the ruins of Pergamum climbing the sometimes steep path up to the the most dramatic acropolis in Asia., thru the Temple of Athena and the agora to the Trajaneum. This was built on a terrace, partly cut into the hill, partly supported by massive arches which also serve as high vaulted storage rooms below. A series of arches follows the lower sections, leading to the Hellenistic theatre carved into the hillside. From here, we walked past the Altar of Zeus [the actual altar was removed to Berlin by German archaeologists], then continued on downhill, passing city walls from several eras, and a series of gymnaisia and a bath complex

At the base of the city, you can visit the Asclepium, the ancient HMO where patients came for treatment and cures. Vaulted, underground passages connect the various sites.

You can do Gallipoli and Troy as a long day trip from Istanbul, but it's much more rewarding to take several days, which then lets you expand to Pergamum. There are good hotels in Cannakale with convenient ferry connections. A guide is highly recommended.