Fore information about this Love Letter: http://www.dailymail.co.uk/sciencetech/article-2514419/The-500-year-old-love-letter-written-mourning-dead-mans-pregnant-wife-buried-Korean-mummy.html
Arguably, letters exchanged between lovers through St-Valentine in the 1400's would be the older of the love letters.
Happy Valentine's Day
Write your own love letters... to:
YOURSELF
People you love
Your gods/guides/totems