The most obvious archaeological feature in Baltinglass is Baltinglass Abbey, sitting on the eastern bank of the River Slaney. This is a daughter abbey of Mellifont, the first Cistercian abbey set up in Ireland. Founded in 1148 by Diarmuid MacMurrough, Baltinglass Abbey is typical of Irish Cistercian architecture. It was built using granite and is in the shape of a quadrangle with an open space in the centre and the church on the north side. It was most likely built by a group of French stonemasons. The stone for the abbey is thought to have been quarried around ten kilometres to the south, near Rathvilly.
Only part of the original structure remains today, including the ruins of the Romanesque church built in the 1100s. In this period, a variety of wooden and cut-stone buildings stood surrounding the abbey. There was also a garden, orchard, beehives, grain kilns, a smithy, barns, and a tannery.
Outside of the town, on the surrounding hillsides, lie a number of other interesting archaeological features. Tuckmill Hill has the remains of a Neolithic passage tomb, called Rathcoran, and two hillforts. Kilranelagh Graveyard lies five kilometres east of Baltinglass, an ancient cemetery with many interesting features. These include the grave of an Irish hero, a holy well, and the Gates of Heaven, two upright stones – if your coffin is passed through these, you will be sent straight to heaven! Further into the woods, there is an old earthen fort and a stone circle.