Jedburgh Abbey was founded around 1138 as an Augustinian priory, one of four Border Abbeys established in the 12th century under royal patronage — along with Kelso, Melrose, and Dryburgh. The surviving nave, tower, and choir give a strong sense of the original grandeur, and the abbey is in better shape than many comparable ruins elsewhere in Britain.
The on-site Historic Environment Scotland museum is worth the time: it displays carved stonework recovered from the site and explains the abbey's history from its founding through the Reformation. Entry is paid, or free with Historic Environment Scotland membership.