The marble walls are such that an echo in the inner chamber will carry for 15 seconds!
(The marble walls; are; such that an echo in the inner chamber will carry for 15 seconds) (an echo in the inner chamber; will carry; T:for 15 seconds)
The marble walls an echo in the inner chamber
are will carry
such that an echo in the inner chamber will carry for 15 seconds
T:for 15 seconds