About McDonald's 28/29 St Mary Street Cardiff. Since 1974, McDonald's has been dedicated to serving quality food and quick service, at an affordable price for our customers. Visit McDonald's 28/29 St Mary Street Cardiff and choose from a menu of favourites, including McCafé® coffee, tasty breakfasts, delicious burgers like our Quarter Pounder®* with Cheese, McPlant, and more! Before you head out, check out the latest offers and order your food ahead on MyMcDonald’s app. Next time you’re looking for a treat, head to McDonald's 28/29 St Mary Street Cardiff . We look forward to serving you!