Ales Stenar Ship Setting:  This is 67 meters long megalith monument comprises 59 stones, each weighing between 4 and 5 tons. This could be a 1,400 year old ship barrow or a prehistoric almanac... no one knows. Although...research by Bob G Lind and the U.K. International Archaeoastronomical Society indicates that this is indeed "The Sunship", a giant sundial, the likes of which you will not find anywhere else on Earth. The stone you see at this end of the Sunship is the tallest and most important stone in the megalith. At the summer solstice, the longest day of the year, the sun sets over this stone. (Click on photo for a larger view)

Megalith definition: (answers.com)

Any large stone which has been sited by humans and which may have been erected as a monument. Most megaliths date from between about 3000 to 2000 years bc. Megaliths may be arranged in rows or circles; the most famous British example is Stonehenge.