On Inishkea South there are many cross-slabs and pillars. One in particular to the north of the harbour is a tall cross-inscribed slab, located at the centre of two outer circles of stones. This appears to be a Pre-Christian monument that was later ‘Christianised’.
The islands boasts numerous archaeological sites and in early Christian times, Saint Columba and Saint Brendan the navigator, founded monasteries here, The remains of which can be still seen today. Inishkea North is best known for its early Christian monastery which flourished here between the 6th and 10th centuries AD.
On the south-west of the island there are the remains of a small church, dedicated to St Columba and built around 540. On the north-east there are three large mounds, known locally as the Baileys – the Bailey Mór, Bailey Beag and Bailey Dóighte meaning big, small and burnt.
A well known archaeologist, Françoise Henri visited the Inis Gé islands in the 1930s and again in the 1950s and found traces of a dye workshop, thought to be used by the monks in an early Christian Monastery for producing purple colour from the shells of the dog whelks. Ruins of a number of beehive huts, used by monks in the Early Christian period and some cross-slabs dating back to the late 7th to 8th centuries AD have also been found.
The islands of Inis Ge were clearly an important centre in the Early Christian period.