Hello and welcome.

I actually don't have a definitive answer to that but definitely more than 750 pieces 😃 Taj Mahal, Millennium Falcon, all the modular buildings, etc have been made on mecabricks http://www.mecabricks.com/en/library?order😛arts

I know that some people put all the modular buildings together and it worked (about 20k parts).

Maximum number of bricks depends on the type of parts you used in your model (number of polygons), the number of different part designs (geometry is shared among same parts), the number of decorations, etc.

The first thing you'll experience is probably your model being very slow to work with before you actually cap your system. Or at least it did not happen to me.

Tip: If you find that your model is slow and you have the black edges displayed. Deactivate the option. It will divide by two the number of parts in the scene. You can also hide groups of parts.

Nice! Thanks for the answer and the tip.

I actually created a city layout including 12 existing modular building.
I think this is far over 30.000 bricks
It starts to slow down but is still working
I think the power of the computer fixes the limit. I have an I7 hexacore + 16Gb RAM + Geforce TITAN GTX

The only problem I encountered is the clipping.
MECABRICKS stops drawing objects if they are too far away from the camera.
I can't see my whole city. I have to zoom in on a specific area.

How do you zoom in on a specific area? And there a way to get a sense of the physical dimensions of your build? I am interest in bringing something I am trying to design into the real world.

I'm having a similar issue where I want to render. But when I try, there pops up an alert reading subtext "Maximum number of objects: 1000 I am currently well below the limit of 1000 (current piece count 964). I'm not attempting to render all of the pieces (estimated at less than 2/3 are in the view of the camera).