Pillar 25 (east of Stupa 1) dates from the Sunga period (2nd century BC).
Between Stupas 1 and 3 is the small Stupa 5 , unusual in that it once contained a statue of Buddha, now displayed in the museum.
Stupa 3 is northeast of the Great Stupa (you pass it on your left as you approach the Great Stupa from the main entrance) and similar...
Temple 31 information
The rectangular Temple 31 was built in the 6th or 7th century but reconstructed during the 10th or 11th century. It contains a well-executed image of Buddha, which may come from another temple as it doesn't exactly fit its pedestal.