Excavations reveal remains of the Viking Fort, medieval walls, the butt of the Norman Powder Tower and a trickle of the River Poddle - a Liffey tributary which once supplied water to Dublin. The still-visible archway allowed small boats to ferry provisions from larger boats moored on the Liffey. Alternative Tour of Chapel Royal & Undercroft takes place when the State Apartments are not available due to State functions.

Adults €4.50, Student/Senior Citizen €3.50, U-12 €2.