Div grows to specific size and coordinated onclick

I want a div to grow to a specific size and coordinate (scaling the content within), and also enlarge slightly to reveal a 'X" close button.
The idea is similar to what we see all the time with banner ads, where they enlarge and then have a close button.
The thing is, i want it to animate-- see it grow and shrink, not just appear at larger size (which is easy to do by showing larger div on top)