If you want to see the major attractions of Budapest – Parliament, Gellért Hill, Castle District, Opera House, St. Stephen's Basilica - in one day, take the sightseeing tour.
These tours are conducted in various languages and usually last about three hours, including so-called photo-stops. In summer you can choose between air-conditioned or open buses. The prices vary depending on the company, type and duration of tour, but the common range is 4000-6000 HUF.