If you ever find yourself in Hungary and want to get out of the filth of Budapest for a couple of days, then i would recommend Aggteleki Nemzeti Park. It was founded in 1985.
It contains 198.92 km² (of which 39.22 km² are under increased protection). It has been part of the UNESCO World Heritage since 1995. The largest stalactite cave of Europe is situated in this area: the Baradla Cave (26 km long, of which 8 km is in Slovakia, which was also part of Hungary before Trianon.
Trianon was a peace treaty signed in 1920 after WWI, but unfortunately there has not been peace in the hearts of the Hungarians since that time, especially for those left outside of their country. Perhaps one day.
Sorry, but sometimes the history lesson is necessary to understand a people and their culture.
If you do make your way to Hungary and decide to go there from Budapest, then i suggest you make it an overnight trip. If is impossible to get there and back to Budapest in one day, unless you drive there. There is a village with great food just outside of the caves. i will post pictures of it tomorrow.