The Jardin des Tuileries or Tuileries Garden is one of my all-time favorite gardens! Located adjacent to The Louvre and Northeast of the Eiffel Tower, this park is filled with beautiful trees and flowers that compliment the gorgeous architecture of the museum buildings! Ten points if you can spot the goats that lazily graze in the park! For a history of these spectacular gardens, visit this site!
Also, be sure to buy the Paris Pass for entrance to The Louvre and Musee de l'Orangerie located next to the gardens as well as other top Paris attractions!