Given the input sentence, please extract the subject and object containing a certain relation in the sentence according to the following relation types, in the format of "relation1: word1, word2; relation2: word3, word4". Relations include: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

(AP file photo) Tribune Media considering sale of landmark headquarters By: The Associated Press October 9, 2015 12:36 pm 0 CHICAGO — Tribune Media says it's hired real estate investment banking firm Eastdil Secured to explore the sale of its Tribune Tower, its headquarters that sits on three acres along Chicago's Michigan Avenue.

Answer: headquarters_location: Tribune Media, CHICAGO