Certain rooms (JKR Comic Relief interview)

[cloud_walkinguk]

No: HPFGUIDX 31010

While checking out the JRK Comic Relief interview to confirm something 
for a story I came across the following question:

Isaac: If you could travel to Hogwarts for an hour, what would you do 
there? 

JKR: Go straight into a certain room, mentioned in book four which has 
certain magical properties Harry hasn't discovered yet! 

 Anyone got any idea what room this might be from GoF?

Frances
PS This is a repost as I forgot to put a subject reference. Sorry 
everyone!

Celebrate Harry's and Draco's 21st birthdays:
http://www.schnoogle.com/authorLinks/Frances_Potter/Coming_Of_Age/
http://groups.yahoo.com/group/HP_comingofage