 It is considered as a particularly valuable resting place for waders, and may be obtained as resting place for birds on passage.About two thousand years ago, Buechberg formed an island in the former flat Tuggenersee lake area, and there was probably at least one Roman watching tower on the hill established.In the early 13th century AD the House of Rapperswil built the Grynau Castle at the most important and strategically river crossing over the Linth river nearby the then nearly landed lake.