the standard of adnominal clause is not the time of speech but the time of event and use a relative tense.
if we standardize a time of speech, we use an absolute tense. if we standardize a time of action or condition took place, we use a relative tense.
in this sentence, 어제 가는 is an adnominal clause which modifies 곳 (in adnominal sentence, 내가 is omitted which is subject and 가는 is a verb) the action of going is taking place with the action of meeting simultaneously.
to study 상대 시제(relative tense), 절대 시제 (absolute tense) in 관형절(abdominal clause) will help you.