The most impressive architecture I've ever seen was from these two consultants from a big-4 consultancy that had been sitting at a desk at the customer site for literally years. They had lunch together, never talked to anyone that I could see, and I didn't even know what they did for the first couple of years.

I walked past their desk one evening after hours and noticed a printed A3 page of their high-level design diagram. It was... spectacular.

It had over a hundred tiny icons, each representing various systems. Triangles for directory systems, cylinders for databases, and little arrows connecting these things.

You have to picture a spider web of connections between dozens of each type of system.

The notion that this could be implemented was absurd beyond all comprehension. Just one of the tiny little arrows was connecting SAP to a custom system vaguely similar to Siebel. This arrow represented on the order of thousands of tables and API endpoints that need to be hooked up. Another arrow connected an Active Directory with a million accounts to an Oracle directory of the same scale. Another arrow represented synchronisation between a cloud-hosted payroll service to an on-premises equivalent product.

Half the systems didn't exist. Three quarters of the connections didn't exist. Most would have to be written as bespoke code. Some of the arrows would in turn require load balancers, distributed systems, and change tracking databases of their own. We're talking thousands of man years of effort to implement this thing.

It was audacious in the breadth of its scope to the point of going past insane into the brilliant daring art that's only possible if you can appreciate it at the right level of understanding.

That understanding was that these two brilliant people had been collecting something like $4K/day each for years and produced something that dares your to call them on their bluff. But nobody dared say that the emperor has no clothes. They pulled it off.

I was truly impressed.