Creating solid model

HI guys, I have a model which I want it to be in solid in order to import ro Vasari, but I tried different solutions and couldnt make it ? attached is the model4_361920268215517697.3dm (4.9 MB)

I do appreciate your help

The one object that can pose a bit of a challenge is the curved part - the rest are just boxes that you can boolean together (once you hide the floors). For the curved part; join the front and back with the sides. You will then get an open polysurface. To close this one you could use EdgeSrf on open edges by open edges.

Note that your version of Rhino is from 2013. Update to the latest SR!