The Ringstrasse is a five-kilometre horseshoe of boulevard around Vienna's old city, laid out where the city walls once stood. On it, in order, are a parliament with Greek temple columns, a city hall in Flemish Gothic, a Renaissance theatre and twin Renaissance museums, and a university in an Italian humanist manner. Each was given the historical style thought to argue for its function, and art history took a term from it and calls the whole thing Ringstrasse style.
In 1857 Franz Joseph ordered the walls demolished and the boulevard built on the cleared ground, the glacis, where nothing had been allowed to stand. It filled over the following decades with the buildings of a confident state. Walking the loop takes a couple of hours. Do it once in daylight for the architecture and once after dark, when the city hall, the parliament and the opera are floodlit and the traffic thins. The stretch by the city hall carries an ice rink in winter, films in summer and the largest Christmas market in the city.