Castle Hill is a field of enormous limestone boulders scattered over a high basin in the Canterbury foothills, like the ruins of some giant's fortress, and it makes no sense until you stand among them. The rocks are weathered into towers, fins, arches and hollows, some of them many metres high, and the tussock between them is gold in summer and silver in frost. Māori called it Kura Tawhiti, meaning treasured place from a distant land, and it was used as a seasonal camp for people travelling to the West Coast in search of greenstone. The surrounding mountains, white with snow for much of the year, give the scene a stern, grand backdrop.
The boulders have become a world-famous place for climbing and bouldering, and on a good day you will see climbers working on the rock, chalk on their hands, pads on the ground. Others come just to wander, and the paths between the rocks are easy to follow. The scene was used in the Chronicles of Narnia film, as the site for a battle, and the connection has attracted fans. Do not climb on the rocks without proper skill, for the limestone is sharper than it looks. A short walk from the car park is enough for most, with signs explaining the geology and history.
State Highway 73, which runs past the site, is one of the great roads of the South Island, a scenic route between Christchurch and the West Coast, and here it crosses a high basin in long, open bends, with views of snowy ranges. The surface is good and the road is wide, with plenty of lay-bys. In winter, the road can be icy and snowy, and chains are sometimes required, so check conditions before you go. The wind blows hard across the basin, and the weather can change fast. Take warm clothing, even in summer.
Springfield, on the way up from Christchurch, has a few services, and Oxford is a bit farther back, so fill up before you climb. In Arthur's Pass, further west, supplies are limited. A flask of coffee and a sandwich are the best companions here, and a quiet half hour among the rocks at dawn or dusk is a real pleasure. Look out for kea, the mountain parrots, in the nearby hills.