Medieval, around AD 1200, from Hildesheim, Lower Saxony, Germany, in the British Museum.
Literally minutes after I posted 'Cabinet of Curiosities', Arabella (doing the crossword by the kitchen burner it's so chilly in our house at the moment) asks me "did you know that the British Museum opened a portable altar they've had since 1902 to discover the relics of 39 saints?"
It's true. The altar was due for an inspection and cleaning, and to the surprise of the curator a large linen bundle was discovered. Within it, each relic was wrapped up individually and labeled on vellum, one scrap even dating from 12th century Germany! The most renowned relic belongs to St Benedict and is wrapped in a 8th or 9th century piece of silk from Byzantium. The names of forty saints are engraved on the altar, and therefore leads us to believe that one of the relics must have been lost at some point in time. However, the safe arrival of the other 39 is miraculous, and they will now be on display in the 19th century section - the date of the latest scrap of fabric.
Trust the British Museum to never bother opening up a 12th century German altar - for over one hundred years.
"Oh rah rah, yah we have sooo many ancient artifacts of religious importance, whot's another eh?"