Mothers and pups hang in groups on the ceiling.

VOA: special.2009.12.07

The four levels of rooms center on a beautiful courtyard with a glass ceiling to let light shine in.

VOA: special.2009.01.11

Stalactites have to hang on "tight" to the ceiling or they might fall off.

VOA: special.2011.04.11

Stalactites have to hang on tight to the ceiling or they might fall off.

VOA: special.2009.12.07

And also places an overall ceiling on the number of warheads that can be deployed on those systems.

VOA: standard.2009.04.08

The ceiling on warheads is 6,000 and the ceiling on strategic nuclear delivery systems is 1,600,".

VOA: standard.2009.04.08