Here's why:
* Common Nouns: These are general names for people, places, or things. They are not capitalized unless they are the first word in a sentence.
* Proper Nouns: These are specific names for people, places, or things. They are always capitalized.
Examples:
* Common Noun: heritage center (a general type of museum or cultural center)
* Proper Noun: The National Heritage Center (a specific heritage center)
So, while "heritage center" itself is a common noun, specific heritage centers with names like "The National Heritage Center" or "The Museum of American Heritage" would be proper nouns.