I thought this project looked really great:
You can also search for "fire pit" at the top of the page for other great ideas and projects.
You can also pick up some kits
Be careful about local fire ordnance's. Please check with the Fire Department before you start your project. I would hate to spend lots of money on bricks or pavers to find out that burning leaves in my area was against some ordnance. Just a thought.
We used large rocks and just situated them into a circular shape in the back yard. We roast marshmallows and hotdogs around ours. And burn some yard rubbish too. There really is no need to dig a pit. After the first burn the grass inside the circle will die along with any weeds too.
@Sheila that is assuming you can actually have outdoor fires. With the drought we have had over the last few years fan bans are in effect for a good portion of the year. and like Warren mentioned above some cities have their own set of rules.
Fire Ordnance's may go as fare as to allow you to burn your leaves , BUT they may tell you how you are to construct you burn barrel, like with fine mesh screen in order to not let sparks escape out the top to set fire down wind. And if they say to use a burn barrel and you get caught using a fire pit. Well let just say I am glad you will be paying the fine not me...Please just make the phone call and check it out. Don't trust what next door is doing as we all know the rules/laws do change.
I have constructed a very nice burning pit with an old washer drum , dug a hole and sunk the drum, putting paving stones around to create a decorative edge, but still leaving a slight lip above to place a safety screen on. I ALWAYS have the screen over, though I have added a couple bricks around to raise it a bit (fire does need oxygen). Always be aware of the burning bylaws. Where I live we are not allowed to burn leaves, so I pack my leaves as tight as possible into black garbage bags and line them up in an out-of-the-way place that gets sun, then wet the contents and seal. Makes great compost.
p.s. This allows for easily and safely dousing the fire with water.