Budapest river cruises are one of the most enjoyable means to get a great view of the historical buildings of Budapest, all lined up by the river Danube. This is a short video of passing by the Parliament building during a day boat tour:

There are a host of Budapest attractions on both the flat Pest side and the hilly Buda side. Most importantly, you will see the Hungarian Parliament, the Gresham Palace, the Hungarian Academy of Sciences, Pesti Vigado Concert Hall, the Great Market Hall, the National Theater and the Palace of Arts on the Pest side, and the Buda Castle, the Fisherman’s Bastion, the Matthias Church, the Citadel with the Statue of Liberty, the Gellert Baths and the 19th century buildings of the Budapest Technical University on the Buda side, plus, of course, the wonderful bridges spanning the river Danube.