The final cost of restoring one of Lucerne's main tourist attractions - the Bourbaki panorama - and building a new centre to house it will be over SFr32 million ($18 million), some SFr4 million more than anticipated.
Announcing the revised figure, the city authorities said in a statement that the local government would pay most of the extra costs. These are largely due to higher building expenses and more cleaning up work than had been thought necessary.
But the authorities said there had been a significant increase in the number of people who went to see the Bourbaki panorama over the past several months.
Completed by the Geneva artist, Edouard Castres, in 1881, the circular painting is the focal point of a new cultural centre on the site of the original building, which was badly damaged by fire.
The centre was opened earlier this year, and also includes a museum, exhibition hall and three cinemas.
The panorama is a vivid depiction of the entry into Switzerland, at Les Verrières in canton Neuchâtel, of a retreating French army under General Bourbaki during the 1871 Franco-Prussian war.
Demoralised after a series of setbacks against Prussian forces, nearly 90,000 French soldiers were allowed into Switzerland on condition that they lay down their arms.
The panorama by Castres, who was a Red Cross volunteer, is an almost photographic record of the army's ordeal on the snowbound frontier. The painting is 40 metres in diameter and 28 metres high.
An official account of the incident said that never before in history had such a large army been interned in a neutral country under such dramatic circumstances. The reception of the "Bourbakis" was the first major aid operation conducted by the Swiss Red Cross.
swissinfo with agencies