I thoroughly enjoyed reading this; first person worked so well, and I can't imagine it being told any other way. Albus as Severus's servant was so well done--he and Harry's interactions were so wonderful. And I love how you had Harry slowly work his way into Severus's heart and give him the son he hadn't had. When Harry asked if he could call Severus 'father,' I sighed happily.
It was also interesting to read about the construction of the Tower Bridge.