In most people's life first job, first salary, marriage, birth of children etc will be some unforgettable happy events. DOB is not an unforgettable event or period, because we do not remember anything about that and during the infancy and childhood years at least t up to 3 years. We remember DOB because we are compelled to repeatedly write same in various papers throughout our life.
I consider my college years as my unforgettable years. That was the period when I got transformed from an innocent bright student to a self-confident independent thinking adult. That was a period of achievements for me in academic and non-academic areas. That was the period when I started travelling long distance alone or stay away from home visiting relatives or appearing for tests and interview. That was the period when I became a voracious reader, debater, orator and developed analytical acumen.
I am happy and privileged to meet a few of my college teachers and a few college mates now also frequently as we work or meet in common platforms.