Question

how was this dome constructed?
as the first ever dome that was completed on the ground and then lifted into
place through mechanical means
as a series of \screen walls\ between eight ribs that are later filled in with tiles
as a double - shell of herringbone brickwork supported by eight tribes from
scaffolding suspended across the opening 170 feet in the air
as a wood truss dome wrapped in terra cotta tile
as a double - shell dome where the outer shell covers one an older romanesque
dome and uses it as a base of support

Explanation:

The dome in question is the dome of the Florence Cathedral (Cattedrale di Santa Maria del Fiore). Filippo Brunelleschi, the architect, used a double - shell structure. The inner shell is made of herringbone brickwork. The construction was supported by eight ribs (not tribes, likely a typo in the option). Scaffolding was suspended across the 170 - foot - high opening. This innovative method allowed the construction of a large dome without the need for a traditional full - centering (a large temporary internal scaffold).

Answer:

As a double - shell of herringbone brickwork supported by eight ribs from scaffolding suspended across the opening 170 feet in the air.