A party tram, exhibitions and other events will take center stage in Hungary's capital Budapest, a vibrant metropolis that marks its 150th birthday on Friday.

But behind the celebrations is an eclectic city increasingly shaped by an uncompromising nationalist government intent on rewriting the capital's history — to the anger of critics.

Since returning to power in 2010, nationalist premier Viktor Orban has embarked on what he has termed an "illiberal" revolution to restore the central European country's "independence" after decades of communist rule that ended in 1989.

As part of this, the government has unveiled ambitious plans to restore Budapest to its "former glory", prompting opposition including from the city's mayor, who wrested the capital from an official backed by Orban's Fidesz party in 2019. 

Hungary's capital was founded in 1873 when cities situated on opposite banks of the Danube river — affluent Buda, historic Obuda and bustling Pest — united.

"It was envisioned as a European-level metropolis, as the capital of Hungary inside the Austro-Hungarian Empire, that will give the nation back its strength and create its identity," cultural historian Tunde Csasztvay told AFP.

One and a half centuries later, Orban is aiming to transform Budapest, which along with its surroundings houses 2.6 million of Hungary's 9.7 million people.

The most ambitious and controversial project is the reconstruction of Buda's Castle Hill, a tourist hotspot and the former seat of kings. 

Historic buildings, partly or wholly destroyed during World War II, have been refurbished. 

'Put things right'

Supporters claim the restoration project — whose costs have not been disclosed — will correct historical wrongs by restoring the buildings to their original state.

"Communism has wreaked terrible havoc… These things must be put right. It's a bit like a pendulum swinging," said Gabor Erhardt, an architect at Mathias Corvinus Collegium, a private educational institution with close links to the government.

"It's a natural process. The only question: are we hysterical or are we jovial and united about it?"

During the Communist era, the whole district was a cultural space, with museums and exhibition areas, but now it houses government offices, including Orban's office in the iconic Carmelite Monastery overlooking the Danube.

Utilising the Castle Quarter as a government district harkens back to the late 18th century up until the end of World War II when it was used for political-administrative purposes. 

"Orban told us that the period between 1945 and 1989 should be erased from the history of the nation, and we are going to retake the castle," recalled renowned Hungarian architect Zsofia Csomay.

Csomay was part of the advisory body on the restoration project but quit in protest in 2016 at the "ideological-political" wrecking of the cityscape.

Making the Castle Quarter into a governing district — with access restrictions and security measures — is "completely against" 21st-century city concepts, aiming to open spaces to the public, she said. 

"They are throwing a lot of money at this project, while the whole city is falling apart and they are not building any social housing at all," Csomay added. 

'Terrible message'

Budapest mayor Gergely Karacsony, a soft-spoken green-liberal, is also critical.

"I believe it sends a terrible message that the government is nostalgic for the political system between the two World Wars, looking down on the people of Budapest from the castle, the former seat of kings," he told AFP.

"Random political and business decisions are made by the government that do not fit into a long-term, Budapest-based approach," he said.

"This raises both urban planning and rule of law issues, as in a constitutional state, it would be inconceivable to ignore the policy vision of the capital's elected leadership," he added.

Karacsony has limited resources to pursue his goals of turning Budapest into a "calmer, friendlier, more climate-resilient" city as the national government levies an increasing amount of money from the municipality.

Moreover, projects elevated to "investments of major importance for the national economy" can ignore some of the procedures that apply otherwise, as well as objections from the municipality.

The government for example authorized Hungarian oil company MOL Group to build its headquarters into a neo-modern skyscraper, which at 143 meters (469 feet) high is far above the 90-metre limit.