In 1993, Hillen returned to Ireland. Between 1994 and 1997, he created a new body of work entitled Irelantis. The Irelantis series is a collection of scalpel-and-glue collages. They are a bizarre hybrid of the everyday postcard visuals, mixed with a fantastical other world. Most of these highly decorative collages, showing landmarks from around Ireland, are no bigger than a postcard.
These works are partly influenced by the famous picture postcards of John Hinde. Hillen adapts these nostalgic images, juxtaposing the familiar touristic shots to create an altogether different and complex image.
The Irelantis series celebrates the imagery of Ireland. Hillen illustrates places such as Newgrange, The Cliffs of Moher, Trinity College and O'Connell Street.
In addition to John Hinde, Hillen has been influenced by many other artists, including the great photomontage artist John Heartfield. This influence can be seen especially in Hillen's more political montages of the Troubles in Northern Ireland.