Stonehenge was built and modified several times over the course of a thousand years
starting around 5,000 years ago.
This kit shows what the final version probably looked like based on the ruins that are there today.
But some of these stones are simply missing so archaeologists can’t know for sure that
this plan was ever actually completed.
These tall structures are called trilithons, and the tallest one is 9 meters, or 30 feet.
There's only 3 of them still standing today, but it would have been just two, except they propped one
back up in the 1950s.
These smaller stones are called bluestones.
The geological source for these is over 200km away, and there’s an ongoing debate
about whether they were carried to the site by people, or by glaciers some time long ago.
Even these smaller stones weigh around 3 or 4 tons, so it would be like moving 40 dead
hippos from DC to Philly without a wheel.
This is a prehistoric project, which means that the neolithic people that built it
didn't leave any written records about why or how they were doing this.
But they did leave behind some clues, like the antlers they used as picks to dig holes.
Because antlers are organic material, they can be radiocarbon dated, which is how archaeologists
can estimate the chronology of all of this.
These outer stones weigh around 25 tons.
Their source was more local, but they still had to be moved some 20 km. and archaeologists
can only guess how they did that.
They’re called sarsen stones and they’re harder than steel but they were shaped into
these fairly uniform blocks using stone tools.
And then they were pushed into pits before being pulled upright.
The stones in the top ring are called lintels and you can’t tell from this model but they
actually had joints - like woodworking joints.
There were grooves in the lintels that fit into bumps on the top of the upright stones and then on the side
of the lintels, they also fit together like puzzle pieces.
And not only that, but the neolithic builders who made this were able to carefully calculate
the heights of all the stones so that the monument was level even though it’s not on level ground.
Grass!
Ta- da!
Except we’re not actually done.
The stone circle was just part of the Stonehenge site.
It sits in a much larger circle that was drawn in the earth with ditches and mounds.
There was an avenue leading up to the entrance of that circle, a big stone on that avenue
called the Heel stone, and four other stones that form a rectangle and may be linked to
certain moon cycles.
This site must have been incredibly important to the neolithic people that built it, but despite
hundreds of years of analysis and speculation, we’ll never know for sure
what it really meant to them.
But we do know that it’s design involved an early form of astronomy.
In the 18th century, a historian noticed that the central axis of stonehenge points toward
the location on the horizon where the sun rises on the summer solstice.
So if you stood in the center of the monument and looked toward the Heel stone, you'd see
the sun rise there on June 21st — it’s not a perfect alignment, but it's close.
Summer solstice is when the sun’s path is furthest north, rising in the northeast and
setting in the northwest.
That makes it high in the sky in the northern hemisphere and low in the southern hemisphere.
This is all because the earth is tilted relative to it’s orbit around the sun, and the solstices
are where the sun’s path appears to pause and change direction.
But the people that built stonehenge didn’t know the earth moves around the sun or spins
on a tilted axes.
They probably didn’t even suspect it was round.
They just saw the sun bring longer days in the summer and shorter days in the winter
and those turning points would have meant a lot for their food security.
And there’s reason to think that the winter solstice was particularly important for the people
at Stonehenge. The winter solstice sunset is on the same axis as the summer solstice sunrise - just
on the other end, toward the southwest.
And the midwinter alignment shows up in other
monuments, like the Newgrange tomb in Ireland which has a window that
allows the sunrise to illuminate the inner chamber on the sunrise of winter solstice.
Archeologists also found pig bones from a settlement near Stonehenge that they believe
were slaughtered in the wintertime, based on the pigs’ age.
Their findings suggest an annual winter solstice pilgrimage and feast.
The idea is that people would have approached
the monument by walking on the avenue, which would have put the midwinter sunset in their
sightline, right in the window of the tallest trilithon.
Historian John North argued that when viewed from this side, the monument’s silhouette
would have looked like a solid black form, with the setting sun bursting through
bringing the promise of another spring.