Mariánské náměstí 5, Prague 1, Czech Republic
222 220 879
These two historic sites are part of the Klemntinum complex. The library was built in the baroque style and has ceilings covered in colorful frescoes. You can reach the Astronomical Tower, which was constructed around 1723, via a very steep staircase. This climb is made worthwhile in the end, though, when you see the 18th-century telescopes, shockingly accurate sundial, precise pendulum clock, and simply astounding views of Prague. The tower, despite its antiquated appearance, is actually still a valuable resource for scientific research today.