Prague's New Town Hall isn't as new as its name might suggest. It dates back to 1377 after Charles IV founded the New Town, and it served as the seat of municipal government until 1784. At that point, the building was converted into a criminal courthouse and prison. Today the New Town Hall building is a heritage center and is used for exhibitions, social events and weddings.
Not much remains of the original building from the 1300s, but today you can see additions and renovations from different periods in history. The Gothic tower, which was added in the 15th century, stands at almost 230 feet tall and offers visitors who climb the 221 stairs views of the New Town and Karlovo (Charles) Square. The south wing of the building was designed in a Renaissance style in the 16th century, and if you look closely, you'll notice a chain fixed to the building. This is from a time when the streets in Prague were closed off by chains.
The New Town Hall is located at Karlovo namesti 23 in the northern part of Charles Square. You can get there by taking metro yellow line B to the Karlovo namesti station. Opening hours are 10am to 6pm Tuesday through Sunday. Admission is CZK 50.