Which metamorphic rock was used to build the roman coliseum slate gneiss marble schist?

The answer is Marble.

Marble is a metamorphic rock which is composed of recrystallized carbonate minerals like calcite and dolomite. It can be used for tiles on the floors, counter tops, and some even used marble to carve statues. It was used extensively in building the Roman Colosseum. 

Probably north korea if your family has decided to use only nuclear power.

I’m sorry i don’t know the answer