They call it the Duna there, but it's the Danube all the same. If you really want to know, Buda and Pest were two cities separated by the Duna for most of their 1100-plus year history. In the 1800s, they were united (sort of like Chicago and Gary, Indiana). To travel between the two halves of the city, there are only a few bridges, of which many are big and old and dirty, some are new, and some are entirely uninteresting.