Balıkesir is an inland provincial capital between Istanbul, Bursa, Izmir, and the northern Aegean coast. It is mostly modern and workaday, so do not expect the drama of Bursa or the seaside charm of Ayvalik. What it does have is a compact centre with a few worthwhile Ottoman and Republican-era sights.
The best short walk links Zağnos Pasha Mosque, the Balıkesir Clock Tower, and the Kuva-yi Milliye Museum. Together they explain the city's two useful historical layers: its Ottoman foundation and its role in the early nationalist resistance after the occupation of Izmir in 1919.
Balıkesir is a selective stop, not a headline destination. It works best if you are already crossing western Turkey by train or road and want a grounded, untouristy city with enough texture for a half day.