The first St Stephan zu Mainz was built in 991 as a side project to the building of the cathedral. (Willigis, the first bishop of Mainz, had a hand in both.)
The current structure was started in around 1267 and they cracked on at quite a pace, completing it a mere 73 years later.
The cloister (this image) was done in a flash by comparison – 37 years.
Various mishaps befell the church over the years – St Stephan took the brunt of a powder magazine explosion in 1857, losing its baroque facade, but protecting the rest of the city from the shock wave.
World war II took away the belfry and the cloister, both of which were rebuilt by 1971.
Chagall windows, anyone?