The Sacred Hall

At Loughcrew in Meath a beam enters Cairn T on the mornings around the equinox and descends the engraved backstone, moving left to right for roughly fifty minutes and picking out circles, cup marks and radial sun motifs in sequence as it goes. The carvings resolve only while the light is travelling over them. Stand in the same chamber an hour later and the stone looks like very little.

The Sacred Hall works the same way: a floor that means one thing in the dark and another when the light reaches it.