Sad-at-Ullah Khan Mosque is an 18th century shrine located at the entrance of the Rajagiri Fort, at Viluppuram
, Tamil Nadu
. It was built by Sad-at-Ullah Khan to commemorate his victory over De Singh and the subsequent capturing of the fort. Certain Persian inscriptions found here record its year of construction as 1718.
Nearest airport is at Chennai. Viluppuram Railway Station is located on the Chennai-Cuddalore line of the Southern Railways. National Highway No 45 passes through Viluppuram.