- Dún Formna
Located on high ground overlooking the harbour in Inis Oirr. This fort was modified in the Late Medieval Period when a tower house was built in the interior. The enclosing wall may also have been rebuilt at this time and the raised ground level in the interior may now partly overlie the foundations of an earlier thicker wall. It is not possible to date this fort by field examination alone as the later modifications now mask any earlier features.