A concept much mentioned in permaculture literature is that of the herb spiral. It is a fine idea fun to do and useful.
The first idea behind a herb spiral is that culinary herbs really should be in the inner most zoned - as close as possible to the kitchen door - so that the cook can pop out and grab a handful of rosemary or thyme.
A spiral or a mound is one way of saving space so that a variety of herbs may be grown together and be accessible but not over crowded. An herb spiral is comparatively low maintenance needs little attention – just a little watering and poking in new seedlings every so often.. Some culinary herbs need more water than others do. Some herbs relish rather dry conditions. In a garden, this differentiation is hard to manage but is possible in the spiral.
Put plants that like wet toes on the bottom and those most tolerant of dry conditions go on top.
The spiral is a gently curving ramp that makes a 360 degree turn. Use rocks, bricks, concrete blocks or short planks held in place by stakes to hold and define the spiral.
Bill Mollison in “Permaculture Two” has a diagram suggesting the following succession going from a little pond at the bottom to the drier top: watercress, mint, marigold, parsley violet chamomile chives, thyme, tarragon, sage oregano and a crown of rosemary.