Zagreb Cathedral
The Zagreb Cathedral, with its towering spires, is a must-see place in Zagreb. Officially known as the Cathedral of the Assumption of the Blessed Virgin Mary, it dominates the city skyline. Construction originally started in the 11th century, though much of what you see today dates back to the late 19th century after an earthquake. Inside, you'll find impressive Gothic architecture, including the sarcophagi of Croatian historical figures. It's a truly impressive sight, and I think it's worth spending some time here, even if you're not particularly religious.
Insider Tip
Visit during a weekday morning to avoid the largest crowds.