Patliputra station se sabhi metro cities ke liye train hai but KOLKATA ke liye koi train nahi. Gorakhpur se Kolkata ke liye Train chalni chahiye via Deoria - Siwan - chhapra - Patliputra - Patna - Gaya - Koderma - dhanbad - Asansol - Burdhwan - Kolkata. It will be a profitable route.