At this point Costa became involved. Writing to Andrade from New York, where he was busy building the Brazil Pavilion for the 1939 World’s Fair, he politely expressed alarm that Leao’s design was a capitulation to neo-classicism, a style that Costa himself had recently abandoned, but which still had numerous influential adherents. Costa wondered if the project marked a ‘rejection’ of the Modernism with which he was himself now increasingly identified. He encouraged Andrade to commission a further study with Oscar Niemeyer as the architect; Andrade agreed.

Niemeyer’s design was an uncompromisingly Modernist horizontal block, whose potentially tense relationship with the site was ameliorated by the use of a flat grass roof. This, Niemeyer argued, would make for a building that when seen from above (thinking of the vertiginous landscape of the town) would be hard to separate from the surroundings. Costa was not so sure, and argued for tiles; Andrade agreed and advocated a pitched roof too. The columns on the new design were also designed to be spaced so as to make a visual connection with the pau-a-pique construction of the surrounding buildings. Costa thus won over the traditionalists. His argument was that Niemeyer’s scheme, whatever its incorporation of historic elements, had ‘beauty and truth’. Good architecture, he argued, would sit well in any combination, ‘regardless of its age or style’; neoclassical buildings were only convincing with a great deal of artifice, and in any case they ran the risk of confusing the visitor to Ouro Preto, who might mistake the neoclassical for the authentic. Better a building that was unambiguously modern. In a rare judgement on taste, Costa stated that only ‘new money’ wanted pseudo-authenticity. Only those with really poor taste would want to hide the modern; one who really likes old furniture has no objection to placing a modern telephone or fan on it. The result, in the Grande Hotel, was a building that refused to confuse past and present, making them distinct and legible, without creating a building that failed to fit in with its surroundings.

As a composition, the building was well regarded. Describing the building in 1981, Bruand wrote:
The inclination of the roof, the repetition of a uniform motif on the main floor integrates itself magnificently with the simplicity and lack of pretension of the old buildings . . . far from being a pastiche, the building maintains its contemporary personality, and offers a play of plastic form, resulting from the use of contemporary technology . . . the solution adopted deserves the greatest praise for preserving the integrity of the monumental city.