The St. Mamertus, in a section called the Upper Town, is the oldest chapel in Liechtenstein, dating from the 9th or early 10th Centuries. The tower-steeple would have been added much later, say mid 1400's.
Thanks to the tower, the chapel can be located. From Triesenberg, the community up the mountainside, the tower is visible. Get closer and it disappears in a maze of residential alleys and little streets.
Just keep driving down, and from the bottom, it is again visible. Recalibrate your antennae and start off again, repeating until successful. There are few if any signs, and you are going through a tangle. Suddenly, it all opens up and follow a path to the lovely spot.
Find the Triesen flag and its banner of arms at ://flagspot.net/flags/li-tn.html - azure and white, and the three scythes on the banner represent old families.
For videos of Liechtenstein, try their own website at ://www.liechtenstein.li/en/eliechtenstein_main_sites/portal_fuerstentum_liechtenstein/fl-tou-tourismus/fl-tou-panoramafotos.htm/.