The Dioscuri's adventures take them to all kinds of places. Whether it be the wild forests of Calydonia to track down that pesky boar, the city of Athens to rescue their sister Helen, or the many far-flung places they travel to with the Argonauts, there's no doubt that C and P are some well traveled guys. The very fact that they've been so many places makes them pretty remarkable for their time.
Despite the fact that they go so many places, most of the Dioscuri's story is set in and around their home city of Sparta. This city state was one of the main rivals of Athens back in the day, and it's people were known for being strong and militaristic. You can't deny that Castor and Pollux fit belong in their homeland. These guys are tough warriors with no fear in their hearts.