My latest project - again, one of those things that just popped into my head one night and I started modeling, without any real plan, just an architecture idea.
And a short turntable animation ...
The idea is that this is a Mirror Universe design, late TOS timeframe, that slipped through the barrier and was subsequently captured by a Starfleet vessel. They converted it and put it into service, and duplicated it a couple times - they're used as diplomatic transports in areas that are considered potentially dangerous.
Or something like that
. It's not influenced by the Romulan design - it just came from a similar mindset when the Terran Empire needed a design to keep the systems in line