Old Sarum
Foundation of Sarum Cathedral, used until the middle of the 13th century
It is entirely fascinating to live in an area with so much history. Stonehenge and castle ruins in the same day! There are stories everywhere. And the "new" things are those that date from after 1600. Old Sarum is old. Read the novel, Sarum, by Edward Rutherfurd, if you have the time. The place is prehistoric and onward. The castle/fort at Old Sarum was built by William the Conqueror (1066---remember?), but it was occupied well before his time. The trenches around the outside of the hill were in place before, but the moat around the castle was his. Most of the walls you will see below were faced with hewn stones, which have been scavenged over the years. Only a few are left. The flint stones were used to fill.
Old Sarum was abandoned in the late 13th century, mainly because there was no space for growth and a not enough water to maintain a community. It eventually came into private ownership, but continued to send representatives to Parliament until the early 19th century. You do get a great view of Salisbury and the cathedral from there.
Walking around ruins is one of my favorite things, and Old Sarum is wonderful in that regard---literally a peak experience.