In the area of cultural heritage preservation and fruition the development of electronics and information technologies has opened new scenarios of research in the field of survey, representation and communication of Cultural Heritage. The aim is thus to make the fruition of works of art available to as many users as possible by using survey techniques and multimodal interaction. In this paper we propose a multimodal fruition of a virtual representation of a medieval ceiling, built in the XIV century, which covers the "Sala Magna" in the Steri of Palermo. The research deals with the design of an intelligent relational agent which interacts with the user in a natural way. To address this very issue a vocal guide has been implemented and wrapped around on the 3D model. This guide assists the user during the visit by means of vocal interaction, so the user can easily navigate the 3D model using voice command. An intelligent relational agent embodied into the system, provides user with a more natural and intelligent way of interaction