Both Budapest and Vienna have a major church named after St. Stephen. But there is a big difference.
August 20th is a national holiday: St. Stephen’s Day. He was our first Christian king, and the founder of the Hungarian Kingdom which existed between 1000 and 1918. Born as the son of Grand Prince Géza, his name at birth was Vajk, but he received the Christian name of Stephen after being baptised.
One of the major landmarks of Budapest is the St Stephen’s Basilica (Szent István Bazilika) in the centre of Pest.
If you go to Vienna, the Austrian capital’s main landmark is also a cathedral named after St. Stephen (more commonly known by its German name STEPHANSDOM), however, the Stephen here was the first Christian martyr who lived at the beginning of the first century.