The second-largest building complex in Prague after the castle was a Jesuit college for two centuries. It holds one of the most beautiful library halls in the world and a tower that has measured the weather since 1775. Here's what you're looking at.
The Baroque Library Hall, opened in 1722 and designed by František Maxmilián Kaňka, holds about 20,000 old volumes and a row of historic globes. To protect it, visitors look in from the doorway on the guided tour.
Daily temperature records have been kept at the Astronomical Tower since 1775, one of the longest unbroken weather series in the world.
The Meridian Hall has a thin line on the wall and a small opening: when sunlight crossed the line, it was exactly noon, and a man on the tower waved a flag to tell the city.
Yes, on a guided tour; you see the Baroque Library Hall from its doorway to protect it.
The Jesuits arrived in 1556; most of the Baroque complex dates from the 17th and 18th centuries.
Home to the National Library of the Czech Republic.