how about a minifig scale hogwarts? http://www.flickr.com/photos/88574960@N02/sets/72157632858317817/with/8508642261/
The person who built this is now the “Chief Communications Office” at bricklink.
It seems like this is the person to ask how to build a cone out of bricks! On close inspection, it looks like her sand green conical spires were made with dark gray bricks covered by 1×1 sand green cones. That helps reduce the blocky appearance. I suppose this strategy could be credited to Egyptian pyramid builders.