The newly-opened Ban Don Thong Chai Archaeological Site is an open air museum and situated relatively close to the famous Ban Chiang archaeological site.

Digging ancient history
Bangkok Post, 26 March 2015
At first glance, Wat Chai Mongkol in Sakon Nakhon looks like a typical Buddhist temple. But it houses a recently-discovered archaeological site dating back 1,800-4,500 years.
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Called the “Ban Don Thong Chai Archaeological Site”, the museum has been open to the public since the beginning of the year. The site is about 19 rai with the entrance behind a prayer hall of Wat Chai Mongkol.
Visitors are initially greeted with a blueprint of the temple’s grounds with markings of the 40 pit sites. Brief information is included about the ancient people who lived in this area, outlining three major periods which can be segmented the same way as Ban Chiang.
Full story here.