Of all the medieval castles that once stood within the boundary of modern Glasgow, only one is left, and not in a pristine state, but recognisably standing: Crookston Castle, on its hill above the Levern Water in the Pollok area. It is the second-oldest building in the city, after the cathedral. The earthworks around it are older than the stones; the ring ditch was cut in the twelfth century, by a Norman named Robert de Croc whose family gave the place its name. The walls were thrown up around 1400, battered by the King of Scotland's siege gun in 1489, repaired, besieged again in 1544, and have stood empty for most of the centuries since. They are, against odds, still here.
The earliest fortification on this hill predates anything written down about it; archaeological work has revealed signs of a still older defended site beneath the medieval layers. In the late twelfth century Sir Robert de Croc, a Norman knight, built a timber and earth castle here, surrounded by a defensive ring ditch that survives today. He founded a chapel nearby in 1180, the remains of which have been uncovered. He gave his name to the village of Crookston in the bargain. In 1330 the lands were bought by Sir Alan Stewart, and in 1361 they passed to Sir John Stewart of Darnley. The Darnley Stewarts replaced de Croc's wooden castle with the stone tower house that stands today, around 1400, building inside the older defenses. The hill's defensive logic had not changed: north is a steep drop to the Levern Water, the other three sides easier to defend than to attack.
In 1489 the Stewart Earl of Lennox rebelled against King James IV. James's response was characteristically modern; he sent the country's most famous artillery piece against his rebel earl. Mons Meg, the great medieval bombard now back at Edinburgh Castle, was dragged west and aimed at Crookston. The bombardment virtually destroyed the western end of the castle and produced a quick surrender. Fifty-five years later, on 3 April 1544, Crookston was besieged again, this time by the Earl of Arran and Cardinal Beaton during the Rough Wooing, while the then Earl of Lennox was busy defending the Bishop's Castle at Glasgow Cathedral. Crookston was treated then as the principal house of the earls of Lennox. Arran installed five gunners in the captured castle in May 1544 to hold it. The repaired tower house we now see is largely the post-1544 building, patched after two royal sieges in a single century.
Crookston passed into the dower lands of Margaret Douglas, Countess of Lennox. Her son was Henry Stuart, Lord Darnley, the second husband of Mary, Queen of Scots and the father of King James VI of Scotland and I of England. Tradition says it was at Crookston, under a yew tree on the hill, that Mary and Darnley were betrothed. The tradition is touching, though impossible to confirm, and it became more touching when, generations later, the yew tree died and a model of Crookston Castle, now displayed in nearby Pollok House, was carved from its wood. In 1572 the castle was granted to another Stewart, Charles, Earl of Lennox. The Dukes of Lennox sold it to the Dukes of Montrose in 1703; William Graham, 2nd Duke of Montrose, sold it to the Maxwells of Pollok in 1757. Today it is a Scheduled Monument, maintained by Historic Environment Scotland, and is open to the public free of charge.
Crookston's architecture is the bookish part. The castle has a rectangular main block, strengthened by towers at each of its four corners, producing an unusual irregular X-plan that you only otherwise see at the great Borders fortress of Hermitage Castle. The entrance is on the north side, defended by a portcullis and two doors. Inside, a straight mural stair climbs to the right; ahead is a barrel-vaulted basement with slit windows and an internal well. The hall, on the first floor, was once also vaulted, rising to 8.3 metres above the floor. A turnpike stair in the south-east corner gave access upward to another storey above the hall and to the upper rooms of the eastern towers. There is a pit prison in the basement of the north-east tower, accessible only from above, in the brutal medieval fashion. Climb the modern iron ladders to the top of that tower today and you get the kind of view the Darnley Stewarts paid masons to provide them with: south across the Levern, east to the bowl of the Clyde valley, and on a clear day the Campsies rising blue and pale to the north. Poets including Robert Burns, William Motherwell, and Robert Tannahill have mentioned the castle in their works. Sir Walter Scott, in his 1820 novel The Abbot, claimed Mary watched the Battle of Langside from beneath the castle's yew tree, which is impossible given the topography. The legend, like the tree, was carved from a softer wood than the truth.
Crookston Castle sits on a hill above the Levern Water at 55.835 N, 4.356 W, about five miles south-west of central Glasgow. From the air the hill is a clear green knot in the surrounding suburban grid of Pollok, just before the Levern joins the White Cart Water. Glasgow International (EGPF) lies 4 nm to the north-northwest; Glasgow Prestwick (EGPK) 21 nm south-southwest. From 1,500 to 2,500 feet AGL the castle's stone walls and the encircling ring ditch are visible in winter; in summer the surrounding woodland half-screens it. The view is best from the south or east, where the hill rises most sharply.