Bryn Celli Ddu is a tomb located on the Isle of Anglesey in Wales.
The site dates back to the Stone Age, around 3000 BC. It was opened and excavated around 1929.
The mound was used as a burial chamber, and the experts claim it may have been built by farmers as a calendar and later used to store skeletons for the afterlife.
When the sun shines on the longest day of the year, the whole chamber lights up.
Many items have been found inside the tomb; for example, human remains were found inside, as well as quartz crystal and even some ancient flint arrowheads, small beads, and even sea shells.
You will notice there are flowers and shells inside. I think people bring them to pay respect to their ancestors.
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