The cathedral's bell tower was left unfinished in the 15th century; its soaring Gothic lines are capped by a Renaissance gallery added in the late 16th century, and a bulging spire that dates from the 1770s. You can climb the 297 steps to the top for excellent views – the entrance is in the Third Courtyard (admission is not included with Prague Castle tour tickets).
In addition to the view, you also get a close look at the clockworks, dating from 1597. The tower’s Sigismund Bell, made by Tomáš Jaroš in 1549, is the largest bell in Czechia.