Historic Resources Committee

check out the City of Philadelphia - Philadelphia Historical Commission  www.phila.gov/historical   The PHC has created/designated several neighborhood - districts (as well as numerous individual structures) for some level of oversight and protection.  The PHC Rules & Regulations are on their website and while they may not be perfect nor totally applicable to the needs of your city they are a good example of what has been done in a mid-major metropolis.  You might also want to contact the Preservation Alliance of Philadelphia - this is a non-profit group not associated with the city government - they will also be able to give you additional examples of how other cities/communities address the issues your concerned about.
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Carl Dress AIA
Principal
Heritage Design Collaborative
Philadelphia PA
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Here in St. Louis, the same authorities that review exterior alterations of historic properties review demolitions as well. It doesn't prevent as many demolitions as you would think, but it does provide a bit of a pause in which preservationists can mobilize more market-driven solutions.

http://stlouis-mo.gov/government/departments/planning/cultural-resources/cultural-resources/index.cfm

Hope that helps,
lisa

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Lisa Selligman AIA
Red Dot Studio, Inc.
Saint Louis MO
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