The site of Old Caerlaverock Castle is in woodland behind the more famous Caerlaverock Castle, and stands on a square platform surrounded by a moat.
The old castle was built around 1220 by the Great Chamberlain of Scotland Sir John De Maccuswell (an early spelling of Maxwell) following a grant of land from Alexander II. However it appears to have only been used for a short time, as around 1270 work began on its more famous neighbour, and the old castle was soon abandoned.
Before 1998 the site consisted of an earthen mound surrounded by a moat. Following excavations in 1998 and 1999 wall footings were revealed, giving a picture of the castle which once stood here. The top of the mound, measuring around 27 metres square, was encircled by a curtain wall. Inside this wall were a number of buildings, including a two storey block at the east corner measuring around 10.5 metres by 7.5 metres.
Immediately to the south of the castle mound a harbour was found, which would once have been linked to the Solway Firth.
It was discovered that many of the buildings had no real foundations, instead being built directly onto the natural silt and clay. There was evidence that some of the walls had moved in antiquity, which possibly led to the construction of further towers at the north, west and south corners of the curtain wall.
This structural instability may also possibly explain why the old castle was soon replaced. Archaeomagnetic dating of burnt clay in the main hall suggests that the it was last used between 1250 to 1275, or 1250 to 1310, covering the date at which the new castle was built.
Today the remains of the wall footings can be seen, along with a section of metalled courtyard.