The ADA requires all public buildings to provide reasonable accommodations for the disabled. Owners of historical buildings will often resist adaptation because they feel that creating wheelchair accessibility compromises the historical value of the structure.
According to the ADA website, modifications and alterations can be made to a historic building if they comply with ADA Accessibility Guidelines (ADAAG) or Uniform Federal Accessibility Standards (UFAS), both of which govern new construction for existing buildings.
If modifications cannot be made following the ADAAG or UFAS guidelines, alternative methods may be used in consultation with the advisory board for each organization.
In such rare cases when minimal modifications established by the ADAAG and UFAS cannot be made because they threaten the integrity or historic significance of a structure, program accessibility must be provided.
A more thorough Q & A is provided on the ADA’s website.