Kaldurg Fort, locally known as Kalmegh or Nandimal, is a hill fort in Chahade, Palghar district of Maharashtra, perched about 475 meters above sea level on the Sahyadri range. Believed to have been built by the Bimb king of Mahim, it guarded the Chahad Ghat trade route and watched over the Surya and Vaitarna rivers.

Its simple rectangular plan is split into upper and lower sections by a natural rock terrace, linked by a few stone steps, with remnants of water tanks hinting at its former role as a self-sufficient outpost. Today the fort draws trekkers for its moderate climb and panoramic views of the Arabian Sea and surrounding valleys, even though little remains beyond its rock-hewn walls and terraces.