Suburban Cathedral

From the introduction:

Across town, various metal panels have been riveted into the ground. Some of these have even been found inside buildings. The panels have been put in place by a labour of molemen—soon after the ground opens up in a fissure immediately beneath the panels. These fissures can be followed down into an enormous cavern five storeys deep into the earth. Out of the centre of this cavern rises a grand cathedral-like building of ruddy stone and marble.