In R-1AA, R-1A, R-1, R-1N and R-2A zoning districts an Accessory Apartment, Accessory Cottage, or Garage Apartment may beallowed as a second dwelling unit on a single-family building site under the following conditions:i) Accessory Apartment.(1) Inside the Traditional City, one Accessory Apartment shall be allowed as a Permitted Use when the building site is at least 1.5 times theminimum lot size for the applicable zoning district.(2) Outside the Traditional City, one Accessory Apartment may be allowed as a Conditional Use in accordance with the regulations andprocedures provided in Chapter 65, Part 2D, when the building site is at last 1.5 times the minimum lot size for the applicable zoningdistrict.ii) Accessory Cottage.(1) Inside the Traditional City, one Accessory Cottage shall be allowed as a Permitted Use when the building site is at least 2.0 times theminimum lot size for the applicable zoning district.(2) Outside the Traditional City in the R-1AA, R-1A, R-1 and R-1N Districts, one Accessory Cottage may be allowed as a Conditional Use inaccordance with the regulations and procedures provided in Chapter 65, Part 2D provided that the building site is at least 2.0 times theminimum lot size for the applicable zoning district.(3) In the R-2A district inside and outside of the Traditional City, Accessory Cottages shall be a permitted use provided that the minimumbuilding site area for an Accessory Cottage shall be the same as that required for a duplex development.

We are hoping to stop by this summer and check out the historic districts. 

Superior, land,  or district court?

If you haven't already, for the ones you're most interested in working with, check your district court to see if they have any evictions. 

Zillow seems to be a good resource for things like crime and school districts.

I am in the process of completing renovations on a historic home in the San Marcos, TX Heritage district.

Their taxable value total on the local tax district site is $315k.

Are you going to have to re-do all the electric inside  The house is old, but not in a historic district, so it is not subject to any additional regulations.The electric will need further evaluation.  

I'm an accidental real estate investor because I bought this house to keep my son in a good school district when we were moving from my old school district to the current.

@Timur Salikov I have friends with modern Airbnbs in the Coronado Historic District near downtown Phoenix where hipsters are flocking.