Buy & Hold Property built on a "double" lot. What do I do?

[Taber Roberts]

I've owned a rental property in the Kirkwood/East Lake neighborhood of Atlanta for over 10 years. The 100 year old 3/2 house is built on a "double lot", which gives it a nice size yard for intown living and a nice feature for prospective tenants.  

I'm happy with the cash flow I've realized over the last 10 years, but I wonder if I'm leaving something on the table.  It seems like I should be doing something with the other half of my lot!

• Can I split the lot and sell half of the lot that the house isn't occupying?
• Should I build another property on half the lot?
• Is there anything else I should consider doing?

I have an existing mortgage on the property so I'm not sure how that impacts my ability to "split" the lot/property.  Does anyone have experience splitting lots in Atlanta or Dekalb County? Any horror stories? Is this even feasible with a mortgage? Thanks for your input and time!!