The Grand Palais is a stone palace wrapped around a hall of steel and glass. The hall inside is what makes it remarkable: its glass roof is the largest in Europe, and the nave beneath runs to about thirteen and a half thousand square metres with nothing standing in the middle of it. Light comes down grey-white and even, so the whole space reads as one open volume rather than a room. Steel arches spring from the balcony level and meet more than forty metres overhead.
It was built as the art pavilion of a world's fair, and it has been fighting its own ground ever since. The soil by the Seine turned out to be spongy, and the builders spent six months sinking timber ten metres down before they could start at all. The same fair left the smaller palace facing it, the bridge between them and the city's first Métro line, so you can walk the whole set in twenty minutes. Fire brought the ceiling down during the fighting for Paris in 1944. The building was shut as unsafe for years and reopened fully only recently; the nave now holds art fairs, exhibitions and concerts.