I decided to put my bonfire pit in my hill in my backyard. I wanted to create a flat chunk of land around it that looked natural (I.e., I wanted the hill to naturally flow into the flat area). I love rocks so I used more rocks than I needed to to try and give it a rounded effect.
I need to buy better sod for the bottom.
The whole thing took me about 2 weeks to build - which was way too fast and next time I would give myself 3+ weeks. I did the whole thing by myself and except for the gas it took to drive the rocks around it cost me a total of $40 (for the sod).
My process:
Step 1 - spend all winter reading about retaining walls
Step 2 - hand pick fieldstone from a farmer's tilled up rock pile
Step 3 - power wash rocks
Step 4 - dig an approximately 16" wide, 12" trench in a U formation
Step 5 - fill trench 3/4 of the way up with 3/4-in limestone rocks
Step 6 - lay a 30-year landscaping fabric over the limestone rocks
Step 7 - place the largest boulders at the front where most weight needs to be retained
Step 8 - dump soil into a tall mound behind the rock wall
Step 9 - Play tetris with rocks layer by layer, backfilling with pea gravel, and dirt while maintaining the landscaping fabric between the dirt and the pea gravel.
Step 10 - dig out the fire pit and line with rocks
Step 11 - dig a 2-ft hole 12 in from the fire pit and use ceramic tubes to create a chimney for the smoke (this was an experiment and it worked!)