BUDAPEST — Augustus boasted of finding Rome a city of brick and leaving it a city of marble. Hungary’s prime minister, Viktor Orban, seems to be trying for something similar.

With two huge building projects, Mr. Orban intends to change the face of Budapest — partly for economic reasons, to lure more tourists, and partly for political reasons, to restore key national edifices to their pre-World War II glory.

The idea, besides removing as many vestiges of Communist rule as possible, is to create a concrete expression of the nationalism his governing party espouses.

On the Buda side of the Danube River, the former royal palace squats grandly atop Castle Hill, blandly remade by the Communists after the destruction of World War II into the current home of the National Gallery of Art and the city’s history museum.

Mr. Orban intends to kick out the National Gallery, restore the palace to its earlier grandeur and install himself in new offices nearby.

On the Pest side, at the far end of Budapest’s grand but financially struggling Andrassy Avenue, the government intends to spend more than $780 million to transform the city’s 250-acre main park into a kind of Berlin-style Museum Island.

It will include a half-dozen new institutions, some designed by major international architects, and other tourist-friendly projects scattered around one of the city’s last major green spaces.

“These projects, when lumped together, probably constitute the biggest such concentrated architectural project in Budapest in 100 years,” said Samu Szemerey, an architect and founder of the KEK Hungarian Contemporary Architecture Center.

Laszlo Baan, general director of Budapest’s Museum of Fine Arts, said it was the largest architectural project in Europe and a transformative event in the city’s history.

Critics speak of Mr. Orban’s “edifice complex,” and his eagerness to leave a concrete imprint on the capital.

“It can only be understood from a political perspective,” said Gergely Karacsony, the mayor of Budapest’s 14th district, which includes the park, known simply as Liget, the Hungarian word for park.

“Orban is trying to take the existing city and put it back to the shape it had before 1944,” he said. “The park is a victim of this whole political machinery.”

....