Flying through the air on his Firebolt, the broom that Sirius had given him for Christmas, Harry contemplated jumping. Looking at the speckled lights of Edinburgh Harry wished he had the courage to just let go and end his miserable existence. But that was not the reason he had flown all the way from Headquarters. Approaching over the horizon lay the reason for Harry's flight. Tall and solid Hogwarts grew impossibly larger the nearer Harry got.
Landing on the front steps of the castle Harry raced inside the castle towards the dungeons. Harry had one thought on his mind as he raced thought he labyrinth halls of Hogwarts. Standing outside professor Snape's office Harry hoped he had not flown to Hogwarts for nothing. He turned the handle and found it to be unlocked. Entering the foul office of his most loathed teacher Harry wished that Snape had bothered to decorate with something other than jarred specimens and dissected animals. Harry crossed the room to the cabinet and found what he had come for.
Carefully removing the fragile bowl from the cabinet, and trying not to spill the precious contents Harry walked from the room and towards the Astronomy tower. Over a half hour and many careful steps later Harry arrived on the roof top just as the sun was rising up on the lake. Now was the perfect moment for what he came for.
There was a reason Harry had chosen the top of the astronomy tower and it wasn't for the scenery. Although Harry had never seen anyone else enter a Pensieve before he was quite certain that they left a body behind. How else did Dumbledore and Snape know where he was when he had snooped on their memories? So Harry had decided to hide his body up on the roof top when he entered Snape's Pensieve.
Placing the shattered tip of his broken wand to the liquid inside Harry was transported inside Snape's memories.