Where is the object from? Who did it belong to? How did it enter the collection? Nowadays, hardly any curator can avoid dealing with these questions before exhibiting or acquiring works of art or other cultural objects. Provenance has become an essential factor for public acceptance of the legitimacy of holdings in national museum collections worldwide as a consequence of two broad trends. On the one hand, a broad consensus on Nazi-confiscated art was reached in 1998 and expressed in the Washington Principles. On the other hand, there have been numerous heated public debates in recent years about the unlawful or unfair appropriation of cultural assets and the possible restitution of such items.1 Concern about the origins of objects is growing for libraries and archives too. Thus, provenance research has become a globally sought-after discipline.