| Madison Boulder Natural Area | |
| Photo Width: | 280 |
| Map: | New Hampshire |
| Relief: | 1 |
| Label: | Madison Boulder |
| Location: | Madison, New Hampshire, United States |
| Coords: | 43.9315°N -71.1678°W |
| Established: | 1946 |
| Designation: | National Natural Landmark |
| Administrator: | New Hampshire Division of Parks and Recreation |
| Website: | Madison Boulder Natural Area |
The Madison Boulder is one of the largest known glacial erratics in North America and among the largest in the world; it is preserved in the 17acres Madison Boulder Natural Area in Madison, New Hampshire. The boulder is a huge granite rock measuring in length, in height above the ground, and in width. It weighs upwards of 5000ST. A part of the block is buried, probably to a depth of 10feetto12feetft (toft). It was acquired by the state from the Kennett family in 1946. In 1970, Madison Boulder was designated as a National Natural Landmark by the National Park Service.