Firstly for interest, a few quick facts about 'King Stephen the State Founder':

Stephen The First (997–1038) was the last Grand Prince of the Hungarian Conquerors in the Carpathian Basin, and the first Christian King of Hungary, crowned by Pope Sylvester II. King Stephen had fought for the unity of Hungary against pagan Hungarian warriors, and also for the independence of the Hungarian Kingdom against Western European troops.

He brought Christianity to the country and established a legal system. Thus the 20th August in Hungary is both a large scale National and Christian holiday - much loved by Hungarians, especially due to the amazing annual fireworks.

Saturday 19 August

From 10 a.m. - Street of Hungarian flavours - From Castle Garden Bazzar to Szilágyi Dezső Square

Concerts at Clark Ádám Square:  Balkan Fanatik, Bagossy Brothers Company, Ghymes, Szabó Balázs Bandája, Ed Philips and the Memphis Patrol

Festival of Folk Arts in the Buda Castle

Sunday 20 August

8.30 -9.30  - Ceremonial hoisting of the national flag of Hungary, followed by the swearing-in ceremony of military officers (1055 Budapest, Kossuth Lajos Square)

Ceremonial speech by János Áder, President of Hungary

10 a.m. - Air and water parade in the section of the Danube in the front of the Parliament

From 10 a.m. - Street of Hungarian flavours

Concerts at Clark Ádám Square:

Kolompos, Tóth Gabi, Supernem, Ferenczi Gyuri és a Rackajam, Póka-Tátrai Regeneráció

10 a.m. - 4 pm. - Guided tour of the Holy Crown in Parliament

5 pm.  - Holy Mass followed by the Holy Right Procession (1051 Budapest, Szent István Square – Saint Stephen’s Basilica)

9 p.m. - Fireworks display in the section of the Danube in front of the Parliament

Source: augusztus20.kormany.hu