Info from the book Mysteries of the Ancient World, edited by Judith Flanders, (Weidenfield & Nicolson, 1998):
"We have seen that Iron Age temples were once assumed to be rare throughout the Celtic world, yet an increasing number of Late Iron Age examples are now known. Numerous four-sided compounds, or Viereckschanzen, have been found in southern Germany and the Czech Republic. Some are likely to be farms, but others have shrines or temples in one corner, and deep wells which might have served as ritual shafts. The famous stone head of a god, again wearing a torque, was buried, perhaps after being deliberately broken, just outside the Viereckschanzen at Msecke Zehrovice.
The most important new evidence for Late Iron Age religion has come from northern France, where Roman temples were often built on the sites of Iron Age shrines. At these shrines the definition of a sacred space by a ditch may have been more important than a house or temple for the god. Underneath the Roman temple at Ribemont-sur-Ancre Iron Age ditches enclosed a square compound, in at least two corners of which long bones, mainly of people, intermingled with weapons, were carefully stacked around a post. Nearby were the remains of headless human torsos, which may have been displayed around the edge of the compound.
At Gournay-sur-Aronde, the first Iron Age structures were aligned on the cardinal points of the (modern) compass and later on a temple was built on this alignment. The brilliant excavation and analyses of this site have shown how animal sacrifices were placed in a pit in the centre of the enclosure before their remains were carefully laid in specified places of the boundary ditch. The human remains also appear to have been dismembered, in much the same way as the numerous finds of weapons. The reconstruction of the Iron Age temple suggested by the excavators is very similar to the types found later on in Roman Gaul. The sorts and methods of sacrifices and the precise, symbolic, use of space at Gournay-sur-Aronde reveal the site as a microcosm. It lays bare, and is a symbol for, the ways in which the ancient Gauls tried to understand their world.
The existence of cult sites such as La Tene and temples such as Gournay-sur-Aronde with their evidence for repeated rituals involving the sacrifice of people, animals and worldly goods, suggests that these sites served communities and that religious specialists may have been in charge of them.
In this respect the archaeological evidence and the testimonies of the classical writers complement each other. As well as feeding the gods, one of the most important roles of blood sacrifice is divination; determining when is a good or bad time to do things. This also requires the making and marking of time, and a traditional knowledge through which to interpret the omens.
Such then is the image which emerges of the ancient Druids. Romanticism, whether ancient, modern, or New Age, has treated the Druids in the same ways as mysterious, mystic, noble and other worldly. Always as different, as ‘other’. Yet they were also trying to understand their own world, their gods and their own futures. That world was very different, and it was not romantic.”
Also, regarding Bryn Celli Ddu -
Notes from 'Wales – Castles and Historic Places' [CADW]:
“Further indications of elaborate ritual were found in front of the entrance, including a pit containing an ox skeleton. Perhaps the monument should be seen not only as a tomb, but also as a temple at which relatives of the dead came to worship and leave gifts.”
And to highlight an excerpt from the previously-posted passage from the webpage in English:
“The Celts rituals had a variety of meaning, there is fact that a single old oxen was sacrificed in the large central pit and left to decompose. They performed this ritual as an offering to the underground divinities to ensure the potential fertility of the Celts oxen herds.”
Something is not right. This message is just to keep things from messing up down the road