Plans to modernise ‘Paris’s ugliest building’ at a standstill after clashes over plans and pricing

It has been called a carbuncle on the Paris skyline, a sombre skyscraper where visitors to its viewing platform often joke that the city looks better when you can’t see the building itself.

The much-maligned Tour Montparnasse, a lone, dark monolith with tinted windows rising above a historic neighbourhood in the south of the city, is once again at the centre of controversy after its long-awaited renovation was halted this week because of disagreements between its many private co-owners.