Built where kings lived
The site was the Royal Court, the home of Bohemian kings from the 14th century. The Powder Tower next door was once part of it.
Prague's Art Nouveau showpiece was built on the site of the old royal court, decorated by more than 30 Czech artists, and was where Czechoslovakia was declared in 1918. Here's what you're looking at, and what to listen for when you get there.

The site was the Royal Court, the home of Bohemian kings from the 14th century. The Powder Tower next door was once part of it.
On 28 October 1918 the National Committee declared an independent Czechoslovakia here, as the Austro-Hungarian Empire collapsed.
Alfons Mucha decorated the Mayor's Hall: the ceiling and walls show the virtues of the Czech people. It's only seen on a guided tour.
An Art Nouveau civic building finished in 1912, with Prague's Smetana Hall, restaurants and a café.
At the Municipal House, on 28 October 1918.
Yes, the Mayor's Hall is shown on the building's guided tours.