A tale of two stones
The main architecture of Stonehenge consists of two distinct types of stone, sourced from completely different areas. The larger, more dominant stones are sarsens, a type of silicified sandstone. Geochemical analysis shows that 50 of the 52 remaining sarsens came from a specific area called West Woods, approximately 25 kilometers north of the monument. These large stones form the outer circle and the inner arrangement of five trilithons (two upright stones topped with a horizontal lintel). The uprights of the outer circle weigh around 25 tons each and stand about 4 meters high, while the largest trilithon uprights reach 9 meters and weigh over 40 tons.
The smaller stones are collectively known as bluestones. This term includes a variety of rock types, primarily dolerite and rhyolite. Their geological origin has been traced with high certainty to the Preseli Hills in Pembrokeshire, Wales—over 240 kilometers away. The bluestones, weighing between 2 and 5 tons, were arranged in different configurations inside the sarsen circle over the centuries. Radiocarbon dating suggests the first bluestones may have arrived as early as 3000 BCE, while the massive sarsens were erected between 2600 and 2400 BCE. The logistical challenge of transporting these multi-ton stones across such a great distance without modern technology is a subject of intense archaeological debate.
Celestial alignments and ceremonial construction
Stonehenge is precisely aligned along a solar axis. When viewed from the center of the circle, the sun rises over the outlying Heel Stone on the summer solstice, the longest day of the year. In the opposite direction, the sun sets between the uprights of the tallest trilithon on the winter solstice, the shortest day of the year. This astronomical orientation extends into the surrounding landscape. A nearly 3-kilometer-long earthwork path known as the Avenue connects Stonehenge to the River Avon, and its final stretch is aligned with the summer solstice sunrise.
The construction itself displays a high level of sophistication. The builders shaped the massive sarsens using techniques usually reserved for woodworking. To secure the horizontal lintels on top of the uprights, they carved protruding tenons on the uprights that slot into corresponding mortise holes on the underside of the lintels. To connect the lintels of the outer circle to each other, they used tongue and groove joints. This precise joinery, executed on a monumental scale, is unique among prehistoric stone circles.