Adjective of "heritage"

I have seen a large number of instances where heritage is used in an adjectival sense, including heritage structures itself.

We have a regular heritage walk for the interested, as part of heritage tourism aimed to create heritage awareness, where the walkers visit prominent heritage structures.

Let me hasten to add that I am not sure if all of it is grammatically correct.

I assume historical/historic does not work for you because they are not noted in histories of the region, just older. How about older?

Some more possible synonyms, which may or may not work, depending on what you're trying to say: traditional, vintage, conventional, ancestral, period

Historic does seem to be the best choice in your example, but hereditary can also be an adjective form of heritage in other cases.

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