Depends what you want to do with it. If you want to keep it liquid, you can just keep it in bank accounts in major banks. Split it across several major banks. If they all go under, your problems will be far bigger than money. You can also have multiple savings accounts with each bank to garuntee 250k in each one and earn maximum interest. I have 6 savings accounts with my bank each with ~200k in it. If the balance exceeds 250k, the interest rate dtops down from 4.25 to somethink like 1.15.

If you dont need to keep it liquid, you buy a stable asset like land. You might choose to buy a bumch of houses and apartments in the city, but that comes with strata fees and property management etc. Plus, being a landlord investing in residential property makes you a shitcunt. In my case, I purchased rural land. I purchased land adjacent to nature reserves, with about 450ha of arable land, 110ha of forested land, and 85ha of salt damaged land. Im remediating the 85ha of salt land, and strategically planting out about 10 trees/year/ha on boundaries of my arable land to reduce soil erosion and degradation. I lease the land to a couple of organic grain growers who work the land. At any given year about 1/3rd of my arable land is fallow. (Note tgat im not a farmer by trade, I just think its a good, sustainable asset that I can use to directly improve the environment)