Budapest's buildings are strictly secular.
Budapest . It has around 80 geothermal springs , the world 's largest thermal water cave system , second largest synagogue , and third largest Parliament building . Dohány Street Synagogue . It seats 3,000 people and is a centre of Neolog Judaism . Matthias Church ( Mátyás-templom ) is a Roman Catholic church located in Budapest , Hungary , in front of the Fisherman 's Bastion at the heart of Buda 's Castle District .