When Matt and I bought our broken-down 19th Century farmhouse we decided to keep the original floor plan. That meant that we would have several small rooms on the first floor instead of the popular open concept plan. We also decided that we would keep or re-install doors on all of the rooms.
Of course you can't just go to the local big box home improvement center and buy a door that will look right in an antique home. We spent hours looking for the right doors. Often we'd find the door at a salvage yard. Usually it was missing it's door knob. Again, it would have looked all wrong for us to put a modern door knob on these doors.
Because there are so many doors facing each other in our home, we decided that antique glass door knobs would lighten up the space. We were pleased to find that we had a lot to choose from.