How do I access the higher floors of the Clock Tower?

So far you've never been on any of the upper levels.

And you still don't see a way to climb up from inside the Tower.

You have, however, planted the seeds of a plan that will allow you to climb up another way.

Remember what you planted?

That tree you planted in the Post Office yard will hopefully have grown a lot by now.

Now you only need to access that yard.

Use the fountain portal to time travel to the 50s (the present-day Post Office is locked).

Enter the Post Office and go out to the yard.

Your little tree has grown so much!

Look up to see how far it reaches.

While looking up, tap the tree to climb it.

Once on the tree, tap the window of the second floor to enter the clock tower.