I would love to have seen what these looked like originally, but thankfully there is enough preserved that we can get an idea. At Clonmacnoise the original high crosses from the site were placed inside the visitor’s center in 1991 for safe keeping. Replicas (and pretty good ones, in my unprofessional opinion) have replaced them outside in their original spots. The showpiece is the Cross of the Scriptures. The title is self-explanatory.
Soldiers guarding the tomb of Christ, the arrest of Christ, Flagellation and in the centre of the ring the Crucifixion. This cross is decorated with figure sculpture on all four sides. The Cross of the Scriptures was mentioned twice in the annals of the Four Masters, first in 957 and later in 1060. ~Megalithic Ireland
Photos are from my April 2013 visit.