At one time, the place was thought to be Olenacum, but that place is now considered to be at Slack, and Verbeia is now the preferred name for this site.
http://www.pastscape.org.uk/hob.aspx?hob_id=49938
http://roman-britain.co.uk/places/ilkley.htm
http://www.archaeology.wyjs.org.uk/romanweb/Ilkley.htm
For a good map of the fort and roads, see:
http://www.pjoarchaeology.co.uk/commercial-consultancy/castle-hill-ilkley.html