Most Suzuka visitors already pass through Nagoya without ever really seeing it — it's the base for the race, not the destination. That's worth correcting with one full day, either before the circuit takes over your schedule or after the race, while you're still in the region anyway.
Nagoya Castle is the obvious anchor, and it earns the visit. See live rating and reviews on Google Maps. The main keep is a postwar reconstruction, but the Honmaru Palace within the castle grounds is the real draw — a genuinely faithful reconstruction of the original Edo-period structure, with gold-leaf paintings and interior detail rebuilt to match historical records rather than a generic castle-museum treatment. Budget a couple of hours here if the palace interior interests you, less if you're mainly there for the grounds and the photo.
From the castle, Kinshachi Yokocho sits right at the gates — a food street built specifically around Nagoya meshi, the city's own regional cooking, rather than a generic tourist food court. See live rating and reviews on Google Maps. That means the dishes Nagoya is actually known for: hitsumabushi, grilled eel served over rice in a wooden tub and eaten three different ways through the meal; miso katsu, a pork cutlet under a dark hatcho miso sauce; miso nikomi udon, thick noodles simmered in the same miso until they're almost chewy; tebasaki, the twice-fried peppered chicken wings; and ankake spaghetti, a local oddity of thick peppery gravy over pasta that exists essentially nowhere else. Several of the stalls are outposts of the long-established Nagoya names — Yabaton for miso katsu, Yamamotoya Sohonke for miso nikomi udon, Nagoya Bicho for hitsumabushi — so you're not trading quality for the convenience of having them in one place. It's the easiest single stop for eating your way through the city's signature dishes, and a natural lunch straight off a castle visit.
Osu is the other essential stop, and it's a genuinely different kind of neighbourhood from the castle grounds — a dense, slightly chaotic shopping street mixing electronics, vintage clothing, temples, and street food, closer to Tokyo's Akihabara in energy than anything else in Nagoya. Osu Kannon, the Buddhist temple the area is named for, sits right in the middle of it, worth a stop even if temples aren't usually your priority — the contrast between the temple grounds and the shopping street around it is part of what makes Osu interesting. .
