High on the eastern flank of Castlelaw Hill in the Pentlands, two miles north of Penicuick, stand the remains of Castlelaw Hill Fort and Earth House: physical evidence that people lived here for a period of at least seven hundred years.
You reach the site on a minor road that climbs for two thirds of a mile north west from its junction with the A702. The junction is signposted and is found about 2½ miles south of the Edinburgh City Bypass. There is a parking area close to Castlelaw Farmstead, and from there you walk the two hundred yards uphill to the fort and earth house, either on the main path leading up towards Allermuir Hill, or on a grassy path flanked by gorse.
A thought to bear in mind is that Castlelaw Hill Fort stands right on the edge of a military firing range. If red flags are flying to show this is active, make sure you don't stray into the danger area marked on the map displayed close to the car park.
Castlelaw Hill Fort occupies an oval site measuring some 80m by 35m, not counting the ramparts, on top of a shoulder of Castlelaw Hill at a height of just under 1,000ft. If you know what you are looking for and the grass is not too abundant, it is possible to trace the outlines of the fort on the ground, and of the ramparts and ditches which surrounded it, though in places these have been lessened by later rig-and-furrow farming on the site. The ramparts are best preserved on the northern side of the fort and best seen from the north, looking back down the path that leads upwards towards Allermuir Hill and Dreghorn.
Development of the site here began some time around 500BC. At that time this was less a fort than a group of farmers' dwellings, surrounded by a wooden stockade. Some time later this became a proper hillfort, with the stockade being replaced by an earth rampart and ditch. Later still, just before the arrival of the Romans in Scotland in AD80, the fort was strengthened further, with the construction of two further lines of ramparts and ditches outside the existing fort.
There is no evidence of Castlelaw Fort ever having served a defensive purpose, and within a few decades of the Roman's initial arrival in Scotland its use had changed significantly. The main physical sign of this is the earth house or souterrain found dug into the ditch between the outer ramparts during excavations in 1933 and 1952. This has since been given a concrete roof, complete with windows, and it takes a little effort to realise that initially it was a fully underground passageway, like the Culsh Earth House. 20m long, its function seems to have been to provide a cool and dry storage area for agricultural produce. The theory that these structures, which were quite common across the more cultivated parts of Scotland, were actually intended to store grain being traded to the Roman army is supported by the finding of a Roman Brooch and pottery during the excavation of the earth house here.