Concave roof (4)
I believe the answer is:
dome
(Other definitions for dome that I've seen before include "Rounded roof; Greenwich tent" , "Cupola - millennium building" , "Hemispherical roof" , "millennium feature" , "Head" .)
I believe the answer is:
dome
(Other definitions for dome that I've seen before include "Rounded roof; Greenwich tent" , "Cupola - millennium building" , "Hemispherical roof" , "millennium feature" , "Head" .)