The Sethis were the businessmen of Peshawar before partition. These traders earned huge profits in trade with India, Afghanistan and Central Asia. Their residence was built in 1882 by Haji Ahmad Gul. It is a beautiful example of old Peshawari architecture. It is in Sethian Mohallah which has many beautiful examples of Peshawari architecture.
It is right down the street from my house.