Here are some one liners...
Banking on Italy -- The Bank of the "Mountain of Pity" in Siena is the oldest bank still in business today. It may not be in business much longer, but it is today.
Leonardo Joins an Artists Guild -- If you want to work as an independent artist you must join a guild.That doesn't mean you'll actually get work but if you aren't a member of the guild you may very well be locked OUT of work.
1st Printed Book on Astronomy -- The author figured out how to fix the Julian calendar but no one noticed. They will notice this book though.