Hermione's detailed knowledge of the topography of DD's office - Source?

[happyjoeysmiley]

No: HPFGUIDX 185464

Just wanted to know this: 

In DH, Hermione remembers that Phineas Nigelus' portrait is in DD's 
office and ensures that she puts the counterpart in 12 GP inside her 
beaded bag. 

Also, in the chapter "Goblin's Revenge", she states *exactly* where the 
sword of Gryffindor in kept in DD's office. 

My queries:

I can understand if Harry remembers such details about DD's office but 
Hermione remembering them sounds pretty awkward to me. She might know 
who Phineas Nigelus is and what the sword of Gryffindor is all about, 
given her wide knowledge about the WW that she gathers by voracious 
reading. Yet when did we ever see Hermione visiting DD's office so as 
to clearly notice and remember these kind of details?? I can only 
vaguely remember DD helping her to get to 12 GP when Arthur Weasley is 
bitten by Nagini (OOTP) and that too might not have *necessarily* 
happened inside his office. 

Any thoughts? Sorry if this has already been discussed before.

Cheers,
~Joey :)