Art classes of any kind are good, but drawing and design are very good. Does not need to be sculpture or photo but both are OK. Start reading too - magazines about architecture and design, books... Hint: NOT Architectural Digest, but maybe Dwell is a good place to start.

Play many hours of 3d video games. Practice no sleeping and being miserable. Learn how to handle critic from older professors who think they know it all. Learn how to look good in the color black and try to make it look cool.  Get ready to substitute food for coffee.  And also be ready to say goodbye to your social life.  =)

Thanks for the info guys. So does that mean that I don't have to worry about taking sculpturing classes, and photography?

take whatever art classes that inspires you ... You can approach architecture design anyway you want.  Being skilled at sculpture, drawing and photography class will give you the advantage to imagine, spot details and create 3d form more easily.

Anything that gets the creativity flowing! Different kinds of art classes will teach you different things--you can become very skilled at drawing what you see in your head which is really useful in architecture/design, I think doing photography taught me how to really "look" at things and sculpting (using all kind of media) is really great because it helps you to think in 3-dimensions.

As for McGill - have a look at their website. Make sure you are taking the Math/Physics requirement you need (I'm pretty sure McGill has more science requirements than others because their undergraduate arch degree is a BSc.). They also have a list of things they want to see in your portfolio - creative work, etc. This should be able to guide you to choose what kind of art classes to take too.

Also, I would also encourage you to try and do a job shadow at an architect's office at some point - somewhere they will show you the cool part of architecture, the design process etc, but also what else it means to practice architecture, learning about code etc.

Vancity, I know McGill's program and if that is the school (not a bad choice for undergrad I would say), I would suggest you speak with their department. They often hold entrance portfolios Q&A and... sometimes, the professors make themselves available to potential applicants. This way you will understand what that bare minimum skills your portfolio should show. Sculpture and photography are good, but any art class regardless of medium will do wonders.

I would highly suggest life drawing as that is a big part of McGill's studios.

If I were to take sculpturing, would it help if I took an extra  class, or will the basic knowledge from high school art classes do the trick? Also, is a photography course in high school enough? Thanks

Vancity:

I applaud your considering McGill and wish you luck.  It is a great school in a dynamic city, Canada's most interesting.

I would go in this order:  (1) art and design, if not both, (2) sculpture, and (3) photography.  This is because, in architecture school and in the work world, your product will be (1) sketching, drawing, and graphics, (2) model building, and (3) photographing exteriors, interiors, and details.  It would be best to go (1) and (2), if you had to pick 2.

When you insert art and design work of the graphic variety, spend the appropriate time on it and make sure it's good, obtaining your mentors' opinions.  I've seen some good drawings in portfolios for the better American universities. I saw a portfolio with a hand drawing of the Boston skyline and it was impeccable, but this was for the tiny M.Arch. program at UVa and the guy already had a BFA.