The biggest file

We bid on a job a coupla months back that was described in a dwg file that was some dozens of megabytes - it was a reconstruction/widening on several miles of railway line. I'll see this week how big it was and let you know.
Happy Trails To You

I have a small project that is 3.17 Megabyte, but is not finished yet and still has to be rendered as well.

I have several files in the 30-40 MB range. these are mostly 3d buildings in an industrial plant. complete with equipment. piping, duct ect. the plant has an onsite cad guy that has a drawing of the whole plant put together in one file. I bet it is in the 2 gig range. it's great to look at , but a real pain to try & work in to reroute lines or modify equipment.

Yeah I am thinking my lecture theatres might get to around the 15 MB mark when completed. It is OK working on them at home but the office PC is so f@cking slow it takes around 5 minutes to load the drawing and just as long when I pan or zoom.

I have opened a 1.2GB file. You are only limited by your PC's RAM

We do complex 3D piping models that include equipment and structural elements of a plant facility. The machines have 2 GB of memory. 1 GB runs out fast and the computer gets slow and thrashes the hard drive. I had to upgrade them to deal with the models!
AutoCAD's architecture causes it to take more and more RAM as you work, so opening a big model on a machine may seem fine at first, but later on, all the memory is used up. Closing and opening AutoCAD return the used memory to the OS. We may have 30 reference file attached and the total loaded may exceed 200 Meg.
One thing is for sure. 4 GB is the max a 32 bit computer and OS will deal with. Don't know about AutoCAD. -S