While my own house was under construction I lived with a mish-mash of old oak floors, plywood patches, and ancient linoleum for a few years before I was ready to install new floors. Here you can see the old oak flooring piled up after demolition. 

After the old floors had been removed, new 8" wide red pine floors were installed. 

New floors in the dining room and office. 

New floors being installed in the kitchen and living room. 

To get the antique look we wanted, I hammered in masonry cut nails through the face of the planks. It ended up being 2,420 nails (63 lbs worth). It'll be a few years until I forget how bad it was and agree to put new floors in upstairs.

After sanding I applied a preconditioner. This helps even out the color of the stain when it goes down.

After staining and a few coats of polyurethane, the floors were finished. 

A closer shot of the finished floors

Another shot of the finished floor. More pictures of the rest of my personal home renovation can be seen here.