The Zürich opera

Had the pleasure of watching Aida at the Zürich opera house tonight. The basic story is that Aida, the slave girl, and her mistress Amneris are both in love with Radamès, captain of the Guards. Amneris is the daughter of the Pharaoh. But Radamès only have eyes for Aida, and in passing he accidentally betrays his country and is condemned to be buried alive. Aida cannot stand being without him, and sneaks into the tomb, where they await death together. The end. The thing I don't get though is why they could build the Zürich opera house in 15 months in the end of the 1800's, but these days it'll take more than that to build an apartment building with 4 flats!