There are many private philanthropic organizations dedicated to preserving historic properties. If you're the owner of one of these properties, you might benefit from their largesse. Generally, these grants are for renovations or preservation, totaling a percentage of the amount you spend or, in some rare cases, granting preservation funds outright.
For example, the Johanna Favrot Fund for Historic Preservation grants between $2,500 and $10,000 for nonprofit or government agencies renovating historic properties. Similarly, many businesses' philanthropic activities include preservation; for example, the American Express Partners in Preservation program offers grants for the renovation of historic buildings and landmarks.
A plethora of other grant opportunities exist for private, public and nonprofit applicants. The best place to start searching for these grants is through your state preservation office or the nearest office of the National Trust for Historic Preservation.