What is Adirondack lean-to?

An Adirondack lean-to or Adirondack shelter is a three sided log structure popularized in the Adirondack Mountains of Upstate New York which provides shelter for campers. Since their development in the Adirondacks, this type of shelter has seen use in a number of parks throughout the United States, such as Isle Royale National Park in Michigan and Indian Cave State Park in Nebraska, as well as in parts of Canada. It's similar to Nordic laavu.