IV century roman mosaics inside the Mausoleum of Santa Costanza, monumental complex of St. Agnes Outside the Walls, Rome
Built by Costantina, daughter of Costantin I, as a mausoleum near the basilica erected above the catacombs of St. Agnes , it would later become known as the church of Santa Costanza, when Constantina was venerated as saint.
I don’t think it was built by Constantina; I think Constantine I built it for her. It was rehabilitated into a church in the 13th Century.
We don’t know exactly when the mausoleum was built but today archaeologists think it happened beetwen the years 337-351 (after Costantine death) and the peculiar location, Costantina was strongly devoted to St. Agnes, are signs that, maybe, the mausoleum was indeed erected by her. But yes, these are just hypothesis.
The Nebra sky disk, found near Nebra, Sachsen-Anhalt, Germany. It is dated to c. 1600 BCE, and is associated with the Bronze Age Unetice culture.
This artifact weighs 2.2 kg, and is inlaid with gold symbols. It is thought that this disk was an astronomical instrument, and likely also held religious significance. This find reconfirms the abilities and astronomical knowledge of the people of the European Bronze Age, which included the sun’s angle between its rising and setting points at summer and winter solstice, and close observation of the sun’s course over the year. The Nebra sky disk is the oldest known “portable instrument” showing such measurements.
The disk appears to have been developed in four stages (Meller 2004):
1) On the right is the waxing moon, on the left the full moon, and between and above, the Pleiades.
2) Arcs are added on the horizon for the zones of the setting and rising of the sun. Individual stars were shifted and/or covered.
3) The “sun boat” is added.
4) The disk in its current condition. A star and part of the full moon (or sun) was restored.
(The diagrams used are by Rainer Zenz)
Euan MacKie suggests that the Nebra disk can be linked to Alexander Thom’s reconstructed solar calendar from his analysis of standing stone alignments in Britain.