Appleby Castle is in the town of Appleby-in-Westmorland overlooking the River Eden (grid reference [ NY685200] ).
 It consists of a 12th-century castle keep which is known as Caesar's Tower, and a mansion house.
 These, together with their associated buildings, are set in a courtyard surrounded by curtain walls.
 Caesar's Tower and the mansion house are each recorded in the National Heritage List for England as a designated Grade I listed building.
 The uninhabited parts of the castle are a scheduled ancient monument.
Roger de Clifford, 5th Baron de Clifford, ninth Lord Clifford, fifth Baron of Westmoreland (10 July 1333 – 13 July 1389), was the son of Robert de Clifford, 3rd Baron de Clifford (d. 20 May 1344), second son of Robert de Clifford, 1st Baron de Clifford (1273–1314), the founder of the northern branch of the family.
 His mother was Isabella (d. 25 July 1362), daughter of Maurice, 2nd Lord Berkeley.
 He succeeded his elder brother, Robert de Clifford, 4th Baron de Clifford in 1350, on which day he made proof of his age.
Baron de Clifford is a title in the Peerage of England.
 It was created in 1299 for Robert de Clifford ("c."1274–1314), feudal baron of Clifford in Herefordshire, feudal baron of Skipton in Yorkshire and feudal baron of Appleby in Westmoreland.
 The title was created by writ, which means that it can descend through both male and female lines.
 The Norman family which later took the name "de Clifford" settled in England after the Norman Conquest of 1066 and was first seated in England at Clifford Castle in Herefordshire.
 The first Baron served as Earl Marshal of England but was killed at the Battle of Bannockburn in 1314.
 His 8th generation descendant the 11th Baron, was created Earl of Cumberland in 1525, whose grandson the 3rd Earl was a noted naval commander.
 On the latter's death in 1605 the earldom passed to his younger brother, the 4th Earl (see the Earl of Cumberland for later history of this title).
Roger de Clifford, 2nd Baron de Clifford, also 2nd Lord of Skipton (21 January 1300 – 23 March 1322) was a member of the Clifford family which held the seat of Skipton from 1310 to 1676.
 He inherited his title when his father, Robert de Clifford, 1st Baron de Clifford died at the Battle of Bannockburn in 1314.
 His mother was Maud de Clare, eldest daughter of Thomas de Clare, Lord of Thomond and Juliana FitzGerald.
 Roger was also hereditary High Sheriff of Westmorland.
Thomas Percy was a medieval Bishop of Norwich.
 He was the son of Henry de Percy, 2nd Baron Percy and Idonia, daughter of Robert de Clifford, 1st Baron de Clifford.
Robert de Clifford, 1st Baron de Clifford (c. 1274–1314), of Appleby Castle, Westmorland, feudal baron of Appleby and feudal baron of Skipton in Yorkshire, was an English soldier who became 1st Lord Warden of the Marches, responsible for defending the English border with Scotland.
Maud de Clare, Baroness de Welles was the eldest daughter of Thomas de Clare, Lord of Inchiquin and Youghal, Lord of Thomond, Lord of Bunratty Castle (1245-1287) and Juliana FitzGerald (1236-1290).
 She married two times.
 Her first marriage was to Robert de Clifford, 1st Baron de Clifford, 1st Lord of Skipton (1274-1314) on 3 November 1295 by which she had four children.
 Her second marriage was to Sir Robert de Welles, 2nd Baron Welles, Constable of Pendragon Castle (1297–1326) on 16 Nov 1315.
 They had no children.
 She was born in 1276 in Tewkesbury, Tewkesbury Hundred, Gloucestershire, England and moved to Badlesmere to be near her sister, Margaret de Clare, Baroness Badlesmere.
 She died in Badlesmere in 1327 twice a widow.
Henry Percy, 3rd Baron Percy of Alnwick (c. 1321–1368), was the eldest son of Henry de Percy, 2nd Baron Percy (1301–1352), and his wife, Idonea, daughter of Robert de Clifford, 1st Baron de Clifford.
Lady Anne Clifford, Countess Dowager of Dorset, Pembroke and Montgomery, "suo jure" 14th Baroness de Clifford (30 January 1590 – 22 March 1676) was an English peeress.
 In 1605 she inherited her father's ancient barony by writ and became "suo jure" 14th Baroness de Clifford.
 She was a patron of literature and as evidenced by her diary and many letters was a literary personage in her own right.
 She held the hereditary office of High Sheriff of Westmorland which role she exercised from 1653 to 1676.
Robert de Clifford, 3rd Baron de Clifford, also 3rd Lord of Skipton (5 November 1305–20 May 1344) was a member of the Clifford family which held the seat of Skipton from 1310 to 1676.
 He was the second son of Robert de Clifford, 1st Baron de Clifford and Maud de Clare, eldest daughter of Thomas de Clare, Lord of Thomond and Juliana FitzGerald.
 His title was restored to him in 1327 after being forfeited by his elder brother Roger de Clifford, 2nd Baron de Clifford who was hanged for treason.

Question: Robert de Clifford was an English soldier who lived in which town overlooking the River Eden?
Answer: Appleby Castle