Notre Dame
What contemporary architectural components need to be built in the rebuild of Notre Dame?
Probably nothing contemporary to be added.
The roof and other parts that cover the building interior that got burnt down need to be repaired and replaced with a greater material with a great fire rating.
As for the spire, neither that we necessarily need to rebuild it back to what it symbols, nor we need to add whatever which will be symbolic on top of Notre Dame.
Whatever consist of the spire that is damaged, is damaged, and it will be remembered as history.
Perhaps, in this case, the absence will signify the presence in a stronger way than building a new out-of-context presence in signifying an older presence that is long gone.
There is no need to recreate the past in the present context.
The absence of symbolicism (in this case, the spire), will remind us of its presence in the past and its historical event and can be replaced with a skylight that brings light into the church interior.
Pray for Notre Dame and all affected by the fire.