Fill a large pot with water and bring it to a boil.
Add the potatoes and cook for 10 minutes until slightly tender.
Stir in the corn and cook for an additional 5 minutes.
Season the water with Old Bay, salt, and cayenne pepper.
Add the minced garlic and lemon quarters to the pot.
Introduce the crab legs and cook for 5 minutes.
Finally, add the shrimp and mussels, cooking for another 3-5 minutes.
Once all seafood is cooked, remove the pot from heat.
Drain the seafood and vegetables, letting excess water drip off.
Serve hot on a large platter, garnished with fresh parsley.