The first passing landmark was the Battlefield of Antietam. This was the location of the first significant battle of the Civil War to be fought on Northern soil and thought to be the turning point of the war. Although it was considered a tactial draw this battle was the springboard to President Lincoln's Emancipation Proclamation as Union Army Major General George B. McClellan was able to stop Confederate General Robert E. Lee's invasion of Maryland.
Next on my little history trip was Harpers Ferry which is layered with many historical events: the starting place of the Lewis and Clarke expedition; the site of the John Brown raid which precipitated the Civil War; the first command of Stonewall Jackson, who raised and trained his famed Brigade here; the site of three Civil War battles, the major one involving over 30,000 troops on both sides which resulted in the largest surrender of US troops until Bataan in WWII.
So, how do you know when you love your job? For me, I know when I am driving to a high school to meet and teach new students and I am the one that becomes the student.