Yeah it's like a law of reverse propinquity in government. Working with a team next to you in the org-chart is completely impossible. Working with people far removed from you in the department is easier. Working with other departments easier still. Working with private firms and other governments easiest of all.

You're delusional if you think that the people being in the same building changed that whatsoever. And especially if you think that connections across buildings randomly happened without a specific goal.

Sure, you see them in the hallway or in the street, might even nod into their direction if you're feeling particularly social that day... But that's it. And people working in different cities might as well be separate companies.