Question: What landmark is located in Caithness, Scotland, and west of John o' Groats?

Context paragraphs:
Castle of Mey: The Castle of Mey (formerly Barrogill Castle) is located in Caithness, on the north coast of Scotland, about 6 mi west of John o' Groats.  In fine weather there are views from the castle north to the Orkney Islands.

Earl of Breadalbane and Holland: Earl of Breadalbane and Holland is a title in the Peerage of Scotland.  It was created in 1681 for Sir John Campbell, 5th Baronet, of Glenorchy, who had previously been deprived of the title Earl of Caithness.  He, as a principal creditor, had "acquired" the estates of George Sinclair, 6th Earl of Caithness who had died heavily in debt and without issue in 1670.  Campbell was consequently created Earl of Caithness in 1673, but after much litigation and even bloodshed, George Sinclair of Keiss (died 1698), second son of George, 5th Earl of Caithness (died 1643), recovered the estates, and successfully petitioned parliament regarding the earldom, which was removed from Campbell.  Sinclair's title was finally restored to him in 1681.  Deprived by parliament of the Caithness earldom, Sir John Campbell was created Lord Glenorchy, Benederaloch, Ormelie and Weick, Viscount of Tay and Paintland, and Earl of Breadalbane and Holland on 13 August 1681, with the precedency of the former patent and with the power to nominate any of his sons by his first wife to succeed him.  The titles were created with remainder to the heirs male of the son chosen to succeed him, failing which to the heirs male of his body, failing which to his own heirs male, failing which to his heirs whatsoever.  The "of Holland" part of the title derived from the fact that Campbell was the husband of Lady Mary Rich, daughter of Henry Rich, 1st Earl of Holland (see Earl of Holland).

John o' Groats: John o' Groats (Scottish Gaelic: "Taigh Iain Ghròt" ) is a village 2.5 mi NE of the village of Canisbay, Caithness, in the far north of Scotland.  John o' Groats lies on Britain's northeastern tip, and is popular with tourists as one end of the longest distance between two inhabited British points on the mainland, with Land's End in Cornwall lying 876 mi to the southwest.  It is not the most northerly point on the island of Britain (nearby Dunnet Head is further north).

Harrow, Caithness: Harrow is a hamlet on the north coast of the British Isles in Caithness, Scotland.  It lies just to the west of the Castle of Mey and northeast of the Loch of Mey.

Huna, Caithness: Huna is a small remote crofting township, located 2 miles northeast of Canisbay and 3 miles west of John o' Groats in Caithness, in Scotland.  It is currently part of the Highland Council area.  Huna is located 0.5 miles from John o' Groats.

Wick Airport: Wick John O' Groats Airport (IATA: WIC, ICAO: EGPC) is located 1 NM north of the town of Wick in Caithness at the north-eastern extremity of the mainland of Scotland.  It is owned and maintained by Highlands and Islands Airports Limited.

Castletown, Highland: Castletown (Scottish Gaelic: "Baile a' Chaisteil" ) is a village on the north coast of the Highland council area of Scotland, situated near Dunnet Bay.  It is within the civil parish of Olrig, where it is the main settlement, and within the historic county of Caithness.  The A836 links the village with Thurso and Tongue in the west and with John o' Groats in the east.  The B876-A99 links the village with Wick in the southeast.

Dunnet Head: Dunnet Head (Scottish Gaelic: "Ceann Dùnaid" ) is a peninsula in Caithness, on the north coast of Scotland.  Dunnet Head includes the most northerly point of the mainland of Great Britain.  The point, known as Easter Head, is at (grid reference [ ND202767] ), about 18 km west-northwest of John o' Groats and about 20 km from Duncansby Head.  Dunnet Head can be seen also as the western limit of the Pentland Firth on the firth's southern, or Caithness, side (Duncansby Head is the eastern limit).  Although Easter Head is the most northerly point on the Scottish mainland, the northernmost point of Scotland lies in the Shetland islands, approximately 170 miles further north.

Burwick, Orkney: Burwick is a small village and harbour on the island of South Ronaldsay in the Orkney Islands, Scotland.  It is the closest Orkney harbour to the Scottish mainland and is the terminus of a passenger ferry which operates in the summer to John o'Groats in Caithness.

A99 road: The A99 road is entirely within the former county of Caithness in the Highland of Scotland.  It runs generally north/northeast from the A9 at Latheron to Wick and to the A836 at John o' Groats.  It was part of the A9 until the A9 classification was transferred to what had been the A895-A882 link between Latheron and Thurso.  Between Latheron and Wick it follows, mostly, the route of one of Telford's roads.

Supporting paragraphs: Harrow, Caithness Castle of Mey
Answer: Castle of Mey