I have had kids living in NYC and SF, so Central Park, Times Square, Statue of Liberty, Empire State Bldg and Golden Gate bridge are easy. Went to England (niece lives there and got married there), so Big Ben, Tower bridge, and Stonehenge done. Have been to Paris (sister lived there and visited her) so Louvre, Notre Dame, Eiffel Tower, and Versailles. Visited the Grand Canyon and Niagara Falls. Do not have plans to see many of the others, so 14 may be it for me.