One of Berlin's signatures is its half-mile-wide cluster of some of Europe's most famous museums. The best deal will always be the museum-card (especially at the reduced student rate), which allows the holder to come and go in as many museums as they want within a span of three days, barring the occasional special exhibit. But even with three days, the traveler would be wise to focus on a single museum or narrower aspects of all of them: the collections are enormous and their contexts dense.