Rising from the Wicklow countryside 6.4 kilometres northeast of Baltinglass lies Ireland's largest hillfort complex, a sprawling ancient settlement that stretches across the connected peaks of Spinans Hill and Brusselstown Hill. This remarkable archaeological site covers an astounding 130 hectares, making it not just the largest hillfort in Ireland but also one of the most complex prehistoric settlements on the island. The entire complex consists of three distinct fortified areas: the outer rampart that encompasses everything, the Spinans Hill hillfort at 1,346 metres above sea level, and Brusselstown Ring perched on Brusselstown Hill.

What makes this site particularly fascinating is the sheer scale of ancient habitation preserved here. Archaeological surveys have identified around 250 hut structures scattered throughout the complex, with 22 located on the southern slopes outside Brusselstown Ring's rampart and two more within the ring itself. The main defensive works are impressive in their own right; the outer rampart that encircles both hills consists of a double bank with an intervening ditch, reaching 15 metres in total width in places where it's best preserved. At the northern and eastern sections, you can still see the earthen banks covered in peat, whilst limestone boulders form the collapsed ramparts of Brusselstown Ring. Three gaps in the northern section may mark the original entranceways where ancient inhabitants once passed through.

Beyond its defensive structures, the hillfort complex reveals layers of history spanning thousands of years. Within Spinans Hill's interior, archaeologists have identified what appears to be a passage tomb cemetery, including one large cairn and five smaller ones, suggesting the site held ritual significance long before its fortification. A circular stone platform measuring 10 metres across and a 17 metre diameter circular enclosure between two natural mounds hint at possible ritual monuments. Ancient field walls crisscross the landscape, evidence of agricultural activity, whilst the settlement patterns suggest this wasn't just a defensive stronghold but a thriving community. The site remained relatively unknown to modern archaeology until Tom Condit's discovery and survey work in the 1990s, with GPS surveys conducted as recently as 2014 continuing to reveal new details about this extraordinary Bronze Age complex.