When you look at these long-lasting companies, they are all slow-burning concepts with very little competition and little innovation, so you're not going to find suggestions of "technology" companies on this list. The innovator's dilemma cannot be an issue if you want your company lasting hundreds of years. Another problem here is that you need to financialize as little as possible, so you can't have a lot of competition. Investors don't have 500-year time horizons, so those are out (especially VCs). Debt on physical assets seems to be okay when used sparingly.

1. Datacenters or datacenter construction may be the most high-tech ones I would try. Not cloud services, but the literal physical buildings.

2. Musical instruments, art supplies, or other cultural/religious goods of some kind, possibly as high-tech as electric guitars or synthesizers (although those have not historically gone well).

3. Financialization businesses like insurance or securities packaging of some kind could work (if you don't get high on your own supply).

4. Food and hospitality never go out of style.

I assume that the way this sort of business would work is a 3-step process:

1. Start by becoming the best in the world at something very weird and specific.

2. Bootstrap your business with enough connections to start making sales without needing significant financing. Run as a completely bootstrapped business.

3. Convince your children to continue being the best in the world at that thing and maintain your values. If you don't have any suitable children, adopt one. Also, make sure to disinherit any children who are not both very competent and fully onboard with the plan - you need to keep the power concentrated in the one or two best successors.

It's no accident that a lot of these long-lived businesses in Japan, where all three of these are part of the culture.

Good question.

One answer would be focusing on basic human activities. People will still probably be eating and traveling in 500 years.

Another would be to figure out and/or develop the “temple” of whatever future belief system or religion one thinks will be necessary and popular in the future. And this could be a currently existing religion; Islam and Christianity will probably be around in some form or another for a long long time.

Building houses? Wooden furniture? Can't imagine this getting out of fashion anytime soon. Methods and materials may change, the mission not so much.

With wooden furniture you are (at least for some time) also blocking release of stored CO2 back into atmosphere, a fate all other wood faces.

The Mars Terraforming Company? Half-kidding.

ecosystems ? terraformed sustainability spots ..