Greeba Castle and its sibling Greeba Towers were designed by John Robinson of Douglas, a self-taught architect whose hand shaped much of Victorian Douglas. He drew the Bank of Mona, now the Tynwald Building. He drew the Falcon Cliff, the Douglas Head Hotel, and the Derby Castle, all in the same castellated Gothic style. Greeba Castle was originally built for William Nowell in 1849, on the site of an earlier property called Booilrenny, perhaps from the Manx boayl rennee meaning place of the fern. It later passed to Edward Windus, whose father was a partner in the London publishing house Chatto and Windus. The Scandinavian name Greeba comes from Gnipa, meaning a peak. The castle sits at the watershed between the east and west of the island.

Manx folklore tells a story about the castle that you can choose to believe or not. According to the tale, an owner of Greeba Castle once lost the property in a game of cards. Rather than accept the loss quietly, he built Greeba Towers directly in front of his former property, deliberately positioned to block the view of the man who had won the castle. The story explains nothing about the architecture, which was actually planned as two related Victorian houses from the start, but it does explain something about the Manx sense of humour. The pair of houses stand close together at the foot of Greeba Mountain. Both still bear their castellated Gothic features. Whether the card game ever happened is anyone's guess.

Hall Caine moved to the Isle of Man in 1894, rented Greeba Castle for six months, lived briefly in Peel, and then bought Greeba Castle outright in 1896. He was 43, at the height of his fame, one of the bestselling Victorian novelists in the English-speaking world. He lived in the house, partly remodelling it, until his death in 1931. For 35 years a novelist who outsold most of his contemporaries wrote at Greeba, looked out over the Greeba River valley and the rough farmland that rolled down toward the old Douglas to Peel railway, and shaped a body of fiction that drew on Manx landscape and culture for material. The house also briefly served as a school. Hall Caine's presence here is now part of the building's identity.

Greeba Castle stands between the fifth and sixth milestone roadside markers on the Snaefell Mountain Course, the road circuit used since 1911 for the Isle of Man TT and since 1923 for the Manx Grand Prix. The castle was already there when the racing started. It was part of the Four Inch Course used for the Tourist Trophy car races between 1905 and 1922, and part of the course used for the 1905 International Motor Cycle Cup races. Cars and motorcycles have been roaring past the castle's gate for more than a century. In any TT week, the front lawn of Greeba Castle is one of the spots where riders are momentarily a blur and the sound, even more than the sight, fills the valley.

Today the castle is in private hands. The surrounding area is mostly farmland, including the Greeba River and the former Greeba Curragh wetland. The summits of Greeba Mountain at 422 m and Slieau Ruy at 479 m rise behind the house. Just down the road are the ruins of St Trinian's Chapel, a roofless medieval church that has its own Manx folk tale about a roof being torn off each time it was built. The former Douglas to Peel railway line runs parallel to the main road past the castle, now a public footpath and cycleway. Whether you arrive on race week or out of season, what you see from the A1 is more or less what the house has shown the world since 1849: a pair of Gothic Victorian buildings, a watershed crest of countryside, and a road that has carried everything from horse carts to MotoGP-spec bikes.