Fort Vastenburg is an 18th-century Dutch colonial fort that sits at the heart of modern Solo, its massive brick walls now largely overgrown and its interior used as an event venue. The fort is not conventionally open as a museum, but the exterior and the great gate are accessible and worth seeing for the sheer scale of the colonial ambition they represent.
The fort has been threatened with demolition at various points to make way for commercial development, and its future remains contested. Its position in the middle of the city, directly across from the old administrative district, makes it one of the more historically interesting reminders of the Dutch colonial period in Java.