Morton Castle
There is a very pretty short walk along the loch to the castle, which sits on the shore overlooking the water. Even on a cloudy day, it's very nice. The loch, by the way, is manmade - the castle originally stood on a hillock in a marsh, it was filled in in the 18th century and allowed to flood, forming Morton Loch.
one tower of the triangular catle
15th century keep
The castle is a 15th century keep with a small triangular courtyard. Only a single wall remains, and the interior of the main hall still stands. Unlike mos tof the castle from the 15th century, it is not based around a tower house -- instead, a two story hall is the main building; a long rectangular structure on the remaining wall had a hall over a vaulted cellar, but no further rooms above it. There is a round tower at one end. It may have been built along the same lines as Caerlaverock, with large gateway towers, but I think it is the triangular shape of the courtyard that prompts the comparison more than anything else.
Apartments were probaly in the gatehouse towers, not over the hall. There was a private room at the end of the hall, but it doesn't have any of the normal accoutrements of a bedroom. The rest of the castle is much less defensive - large windows face the courtyard with few arrow loops or gunports.
the inside of the main hall block
A much earlier castle (dating possibly from the 12th century) was destroyed in 1357, as a result of the Treaty of Berwick, which required the destruction of castles in Nithsdale. It is possible foundations remain from this earlier castle.
The gateway to the courtyard still has one of the large d-shaped towers standing. It is four storeys tall and stands next to the gate and portcullis (now missing).
one of the ruined round towers, from lochside