immured

imprisoned or confined.

buried within or built into a wall, whether respectfully (as with shrines, monuments, or tombs) or as torture (if buried alive).

walled in.

Pompeians were packed inside defensive walls, and they came and went through gates—the Herculaneum Gate, the Vesuvius Gate, the Water Gate. Vestmann islanders, while clustered, were immured by nothing but the sea, and they came and went through their famous harbor.

trapped or captured (within the surrounding matrix).