Question: Walter Scott of Harden lived in what 16th century tower house? 

Context paragraphs:
Harden Castle: Harden Castle is a 16th century tower house, about 3.5 mi west of Hawick, Scottish Borders.  It is alternatively known as Harden House or Harden Tower.

Arnage Castle: Arnage Castle is a country house, incorporating a Z-plan tower house, located around 4 mi north of Ellon, in Aberdeenshire, north-east Scotland.  The tower house dates from the late 16th century, and was extended in subsequent centuries.

Ballymore Castle: Ballymore Castle in Lawrencetown, County Galway, Ireland was originally a 15th century tower house belonging to O'Madden.  A house was added in 1620, and the castle has been much altered since then.

Duddo Tower: Duddo Tower is a Scheduled Ancient Monument and a Grade II listed building comprising the ruinous remains of an ancient pele tower and 16th century tower house, situated on a prominence on the south side of the village of Duddo, Northumberland, England.

Auchenrivock Tower: Auchenrivock Tower is a ruined late 16th Century tower house situated near Langholm, Dumfries and Galloway.  The remains of the tower, which rise 8 feet at their highest, are currently built into a garden wall.

Auchterhouse Castle: Auchterhouse Castle is a c. 13th century castle located northwest of Dundee, Angus, Scotland.  The original castle was enclosed with walls, towers, and contained a keep.  The castle may have been in ownership of the Ramsay family, who were hereditary Sheriffs of Angus.  Sir William Wallace is alleged to have stayed at the castle and one its towers was named in his honour.  King Edward I of England spent the night of the 20 July 1303 at the castle.  The castle came into the possession of James Erskine, 7th Earl of Buchan who may have built the 17th century tower house.

Barholm Castle: Barholm Castle is a tower house located five miles south-west of Gatehouse of Fleet, in Dumfries and Galloway, southwest Scotland.  The tower dates back to the late 15th century, and it was a stronghold of a branch of the McCulloch family.  The present form of the castle dates from rebuilding in the 16th or 17th century, and in the early 2000s it was restored from a roofless state to residential use.  Barholm The tower is sometimes identified with the fictional Ellangowan, in Sir Walter Scott's "Guy Mannering".

Borve Castle, Benbecula: Borve Castle, also known as Castle Wearie, and Caisteal Bhuirgh in Scottish Gaelic, is a ruined 14th century tower house, located at the south-west of the island of Benbecula, in the Western Isles of Scotland.  MacGibbon and Ross attributed the building of the tower to Amie mac Ruari, wife of John of Islay, and dated it to between 1344 and 1363.  It was occupied by the Macdonalds of Benbecula until the early 17th century.

Barnhills Tower: Barnhills Tower was a 16th century tower house about 4.5 mi west of Jedburgh in the Scottish Borders, Scotland, north of the River Teviot, on the high left bank of the Craigend Burn.

Walter Scott of Harden: Walter Scott of Harden (before 1563 – 1629), also known as Auld Wat, was a notorious Border Reiver.

Supporting paragraphs: Walter Scott of Harden Harden Castle
Answer: Harden Castle