Archeological Museum
This museum deserves a lot more attention and visitors than it actually gets. It is small, but contains an amazing collection of findings, mostly from the nearby ancient city Kyzikos. The interior consists of a tiny numismatic room and a larger hall with terracottas, bronzes, marble steles and other small finds. There are also many well-written and informative panels, which are in fact way better than those in some bigger museums (e.g. Istanbul, Ankara, Antalya). They can give you many ideas for trips to several interesting sites in the vicinity of the town.
The open-air exhibition, in contrast, is rather chaotic. There are many beautiful marble artefacts, most of which literary scattered or piled around, with no explanation whatsoever. Worth the visit if you have a day at Bandirma.