What program are these 3D models created with? 

These 3D models are created by using 3ds Max from AutoDesk. Then, they were exported into AutoCAD DWG formats.

How often are these 3D models updated? 

These 3D models are updated from time to time or upon request from the public.

What is the coordinate system and scale of the 3D models? 

Massachusetts Mainland State Plane Feet, NAD1983 is the coordinate system. The scale is one drawing unit equals to one foot. To use the model in architectural scale, scale up the model by 12.

Why are the files in pieces? Where can I download a single 3D file for the entire Boston? 

The files are divided by neighborhoods of Boston because of the file size. If all pieces are put together as one file, the size will be more than 700 MBs. Most 3D programs cannot open the file of such size. Even if it could be opened, it will be very hard to work with. There is not a single 3D file of Boston exist as of today.

How can I put together these pieces into a single file?

For any 3D program (such as AutoCAD, 3ds Max...) that recognizes coordinate system, these pieces are very easy to put together. For Max users, xreference each piece into your scene, they will fit together. For SketchUp users, compose these pieces in AutoCAD. Insert each piece at the insertion point of 0, 0, 0 and then import the composed file into SketchUp.

Which file should I download? 

Download the file according to your project's loaction, you may need to download neighboring neighborhood files. Also download Under Construction Buildings.