On a hill in the southern outskirts of Vienna stands one of the most arresting modern churches in Europe: 152 raw concrete blocks of varying sizes piled at apparent random into a structure that looks like a brutalist Stonehenge. Designed by the sculptor Fritz Wotruba and completed in 1976, it is in some ways a 20th-century answer to Karlskirche — radical, sculptural, polarising.
The interior is unexpectedly luminous, with daylight filtering through gaps in the blocks. Bus 60A from Hietzing gets you there. Free entry; check opening hours, which are limited.