Darby has a number of properties that are on the National Register including the Darby Friends Meeting House,the Darby Friends Burial Ground, and the Boon Railroad Tunnel. Darby also has a large number of properties that would be eligible for inclusion on the National Register and several possible Historic Districts..
Benefits of Historic Designation:
1) Recognition that a particular property is of significance to the nation, the state, or the community
2)Consideration in the planning for federally funded projects
3)Eligibility for federal tax benefits
4)Qualification for federal assistance for historic preservation when funds are available
Procedure for nomination (Paraphrased by John Haigis and  errors and ommissions are his and deeply regretted- Additional (and correct) information can be found on the web site of the Pennsylvania Historic and Museum Commission -See link below.)

Anyone can prepare a nomination to the National Register which is sent to the State Historic Preservation Officer (SHPO) for review. During the review process, , property owners and local officials are informed of the intent to nominate, and public comment is sought. If the property owner (or in the case of a historic district, the majority of property owners) agree, the SHPO can forward the nomination to the National Park Service for their review and additional public comment before actual listing on the National Register. 
Criteria for nomination-Frequently asked questions
Secretary of the Interior Standards
Link to Pennsylvania Historic and Museum Commission
1006 Main
1016 Main
Mt. Zion AME Church
Blessed Virgin Mary Church
1205 Main
home page