This section is from "The American Cyclopaedia", by George Ripley And Charles A. Dana. Also available from Amazon: The New American Cyclopędia. 16 volumes complete..
Altenstein, a mountain castle in Saxe-Meiningen, not far from Eisenach, on the S. W. slope of the Thuringian Forest. It was the residence of Boniface, the apostle to the Germans, in the 8th century, and just behind it is the place where Luther was secreted by the elector Frederick the Wise in 1521. The names of "Lather's beech" and "Luther's spring" perpetuate the memory of the reformer's retirement in this place. The tree stood till 1841, when it was shattered by a tempest, and a part of its fragments are preserved in the church of Steinbach; a small monument marks the place where it stood. Since 1798 Alten-stein has been the summer residence of the court, and has been surrounded by a splendid park. In 1709 a grotto was here discovered, which is among the most remarkable natural curiosities of Germany. It is of vast proportions, and through its whole extent flows a rapid stream of water sufficiently deep to bear barges, and turning a mill at the place where it issues from the earth. The entrance to the cavern is through a subterranean gallery.