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"Park Avenue" is a proper noun, because it is a place. Proper nouns like this should always be capitalized.
It's Proper noun
common noun.
Common
The noun 'route' is a common noun, for example, This is the route to Boston. Any common noun becomes a proper noun when it is used for a specific person, place, thing, or a title such as US Route 66 or the TV show 'Route 66'.
proper
It is a proper noun, because it is the name of a specific thing.
Common
Proper noun
Common
Common noun