Shortly after WWII, a valley in China contained 5 Metasequoia trees. They were evident from the fossil record, but thought extinct for millions of years. Somehow, and no locals know how, three ended up in a yard in our small town. They reach 200 feet. One was about 100 feet with a 10 foot trunk.
Some were sent to the US prior to commie takeover. The USDA sent saplings to nurseries around the country. My Grandfather had a nursery (founded 1929 and still in the family) and my Mom planted it in their backyard. It grew very tall and I climbed in it a lot as a kid.
Visiting a tree farm south of Albuquerque some years ago I was amazed to see another one (much smaller). The owner had gone to China when things opened up there and went to that valley and brought several more samples back. Those are the only two I’ve seen.
Mainau ...snip... is an island in Lake Constance (on the Southern shore of the Überlinger See near the city of Konstanz, Baden-Württemberg, Germany). It is maintained as a garden island and a model of excellent environmental practices... snip....
Mainau Island is a "flowering island" notable for its parks and gardens. Frederick I, Grand Duke of Baden, created the island's arboretum, which now contains 500 species of deciduous and coniferous trees, many exotic and valuable, including fine specimens of Sequoiadendron giganteum (1864) and Metasequoia glyptostroboides (1952).