Esztergom Basilica is the mother church of the Catholic church in Hungary, and is the largest building in Hungary. Apart from the staggering size, the interior is richly decorated and worth seeing for itself. The view from the top of the dome is great, across the Danube bend and over to Slovakia. A great way to approach is by riverboat from Budapest- only in the main season May to September. Free to enter, but there's a charge for going up the dome and for the royal treasury.
WARNING: The train line from Budapest to Esztergom is being reconstructed (planned finish August 2014), so the short journey of 53km is made partly on replacement buses. Expect a journey of almost 2 hours, then a 3km walk from the station to the basilica. A much better option if you don't have a car is to take a bus from the bus station at the east side of Árpád hid (get there on metro M2) to Esztergom. Bus no 800 runs every 40 minutes and delivers you to Esztergom town centre in just over an hour.
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