Boštanj is a formerly independent settlement in the southern part of the village of Veliko Mlačevo in central Slovenia. It belongs to the Municipality of Grosuplje. It is part of the traditional region of Lower Carniola and is now included with the rest of the municipality in the Central Slovenia Statistical Region.

Veliko Mlačevo is a village in the Municipality of Grosuplje in central Slovenia. It lies just southeast of Grosuplje itself in the historical region of Lower Carniola. The municipality is now included in the Central Slovenia Statistical Region. The settlement includes the hamlet of Boštanj south of the main settlement.