Nassau-Siegen was a historical territory in what is now western Germany. It was part of the larger region of Nassau and was established in the 16th century. The territory was ruled by the counts of Nassau, who played a significant role in the political landscape of the Holy Roman Empire. The area is known for its picturesque landscapes and rich cultural heritage. Siegen, the capital of the territory, features historical architecture and museums that reflect its past. The region is also recognized for its contributions to the mining industry, particularly in coal and iron ore.