I have a steep (about 45 degree slope) parcel of land. Mansion has already been built top left of the parcel.

Needing to build a long, flat area beacon to beacon across the parcel so that the mansion can have about a 5m verandah in front of it and a large patio entertainment area alongside it.

What's the best way to go about it affordably without compromising on safety and strength/durability of the verandah-patio?

I was thinking I just build a simple retaining wall with foundation nines to the level of the mansion floor (or slightly higher), columns every 5m, backfill with murram or red soil, do a thin layer of quarry dust blinding, then paving slabs on top mortared together. With some drainage pipes at intervals along the base of the wall.

Would this work?

Any alternative suggestions?

P S. Everyone is permitted to respond to this thread except mjuaji VVS sitting behind a polished oak desk 24/7/365 who's 101% clueless on such matters