>> they've all been here, the celts, the romans, the mongols, the ottoman turks. all had their way or tried. all left their mark to one extent or another. ♪ then mid-19th century, the curious, seemingly improbable austro-hungarian empire. this is when the city came into its open, fueled by untold wealth, accumulated power, and ambition. architecturally, intellectually, a great city. one of the world's greatest. >> and that was a time when budapest was a really progressive metropolis. the first subway in the continent of europe was in budapest. parliament had like a very sophisticated air-conditioning system. so people wanted to come, they wanted to live here, wanted to start a career. wanted to build places like