What element tags can I use inside a hyperlink

Back to HTML school!
I've been complacent and made a schoolboy error! Without thinking too much about it I tried including a whole info box inside a link` <a> This included <p> <h2>
<li> and all sorts.` The idea was to give a larger linkable area for those using tablet touch screens. But alas I can't live with the code errors!
So back to the classroom for me. Its too many variables to use a <style>. Anyone give me an idea of what if any I can use? Is <span> allowed? Can't seem to get it confirmed on looking through w3schools?
(When's it playtime!!)