No, there are no codes for this, and no, you don't actually *have* to have a towel bar if you don't want to. There are many other ways you can handle bath towels, including hanging them from pegs or storing them on shelves. Racks can be wall-mounted, or you can use something like a bookcase or a section of built-in cabinetry you stack them in.

If you choose stacking instead of hanging, you really do need to be sure you've got a way for them to hang loose to dry, or they will mildew, and also likely not be dry for your next shower, so don't plan on returning wet towels to a rack.

You can also do a free-standing rack, or a wall-mounted one, either of which are available in a wide range of styles - can also include a towel warmer. If you've never experienced the luxury of heated towels when you get out of the shower, trust me, you will swoon.

Whatever you choose, yes, it should of course be reachable wherever you get out of the tub, and without contorting yourselves. There is nothing to prevent *also* placing additional towel bars at the end of the tub if you want them there as well, but you do want to be sure that your bathroom is *comfortably* navigable, and you don't go dripping water everywhere - which can also end up a safety hazard as well as an unsightly pain.

The standard height for placement of a towel bar is 48", but you can adjust that as need be depending on your heights and preferences, whether or not they need to be wheelchair accessible, easy to reach for kids, etc. For small children, bars at 36" will work better, especially if you expect the little tykes to hang their towels back up themselves ;->