Since the year 2002, Politecnico di Milano has been developing several educational projects aimed at schools, based on advanced technology (3D virtual worlds, shared over the Internet). The two most recent projects are about history: Learning@Europe (www.learningateurope.net) deals with the formation of European nation-states, and Stori@Lombardia (www.storialombardia.it) with medieval history in Northern Italy. Both projects underwent massive testing in spring 2005, thanks to the support of Accenture Foundation and the regional Government of Lombardy. L@E involved almost 1000 students and 60 teachers from 6 different European countries (Belgium, France, Italy, Poland, Norway, Spain); Stori@Lombardia involved 800 students and 40 teachers from Lombardy region (Italy). A huge amount of data was collected in order to verify the cultural impact of the project. The projects were very successful — beyond our expectations — both in terms of pedagogical impact and of customer satisfaction. The paper will present the most relevant data and the most salient aspects of the qualitative analysis. It will also argue a generalization of this case study, exploring how a deep impact (cultural and pedagogical) upon users can be achieved through technology, and in particular, the role of "virtual presence" in collaborative 3D virtual environments