The Sanchi hill goes up in shelves with Stupa 2 situated on a lower shelf, Stupa 1, Stupa 3, the 5th century Gupta Temple No.17 & the 7th century temple No. 18 are on the intermediate shelf & a later monastery is on the crowning shelf. The balustrade surrounding Stupa 2, carved with aniconic representations of the Buddha, was added in the late 2nd century BC under the Satavahanas. The adjacent Gupta temple no.17 was hailed by Sir John Marshall as one of the most rationally organized structures in Indian architecture. The Buddhas in the perambulatory surrounding Stupa 1 belong to the Gupta period in the mid-5th century AD. The monastery and the temple adjacent to Stupa 1 & the temple near the monastery on the crowning shelf illustrate the evolution of the architectural form after the 5th century Gupta temple.