"Reach the top of the monument" is a mission objective in Sequence 5 / Memory: A Room With A View
Walkthrough[edit]
Turn and head back toward the crowd. If you have yet to let them come forward, do so. This makes it a lot easier to evade all of the Police and the few odd Blighters in the area.
Head for either the side of the moment or backtrack to the building you initially approached the Monument from. From the building, aim for the top of the monument to quickly the top. Get to the marked section and a cutscene will trigger.