Is the word twilight towers a common or proper noun?

Answer 1

The noun 'twilight' is a common noun as a general word for the period of the day just before dark; a word for any twilight anywhere.

The plural noun 'towers' is a common noun as a general word for a tall, narrow structure, a tall narrow building or part of a building; a word for any tower of any kind.

A proper noun is the name or title of a specific person, place, or thing. A proper noun is always capitalized.

The compound noun 'Twilight Towers' is a proper noun in the US as the name of a group of telecommunication structures constructed between 2001 and 2005 that were built without review under the National Historic Preservation Act of 1966. The status of these structures was discussed at the December 14, 2017 Federal Communications Commission meeting where these specific towers were referred to as the 'Twilight Towers'.