Grammar Fix: "Old Chicago Is Our Favorite Restaurant..."

Your sentence has a missing comma and capitalization issue. Corrected version:

"Old Chicago is our favorite restaurant, which is why we go there often."

Changes Made

• Capitalized "Old Chicago" (proper noun)
• Added comma after "restaurant" (non-restrictive relative clause)
• Lowercased "which" (mid-sentence)

Why the Comma Matters

The clause "which is why we go there often" adds extra information—it doesn't define which restaurant. Without the comma, it could imply there are multiple Old Chicagos and you're specifying the one that causes frequent visits.

Alternative Phrasings

• "We often go to Old Chicago because it's our favorite restaurant." (Simpler)
• "Old Chicago—our favorite restaurant—is why we go there often." (Emphatic)