Was it simply a coincidence that in the vast expanse of space between Navarro and the East coast, both the Enclave and Brotherhood of Steel chose bases within miles of each other?

by [deleted]

And if Liberty Prime was built by Mr House in Nevada why did it end up in the Pentagon, a command and control center?

Supacharjed

Yes, it was by coincidence. Both factions on the East Coast both occupied old government buildings, but for different reasons.
Liberty Prime was not built by House in Nevada.
It was built on the East Coast.