Negreira is the first proper town since Santiago and the place to resupply. All services are available -- supermarkets, pharmacy, ATMs, restaurants. The Xunta albergue is on the far end of town, so pick up supplies before you get there if you don't want to walk back.
The Pazo do Coton, a 14th-century tower house near the center, is the most notable building. It now houses the town hall, but the medieval tower is original and gives the town a gravitas its size might not otherwise suggest.
If you're an early-morning walker, scout the route out of town the night before. The camino leaves near the municipal albergue on the west side and passes into dark forest quickly, not emerging until Zas.
"Because I am not inscribed from Noya but from Negreira, where I was born. And from Negreira, which is up the river Tambre, they take you for the army." So says a soldier to his corporal in Ernest Hemingway's For Whom the Bell Tolls.
Hemingway lived for a short time in Santiago de Compostela in 1929, and the impression Galicia made on him was lasting. He referenced it in several novels -- here giving the birthplace to an unnamed character. Some have suggested he also named the protagonist of The Old Man and the Sea after the city, though this remains local lore rather than confirmed fact.
The camino leaves Negreira near the municipal albergue on the West side of town. If you stayed in that albergue, go back towards town a short distance and follow the signs to the church. If you are an early morning (in the dark) walker, do yourself a favor and scout the route the night before. It passes into the dark forest fairly quickly and does not emerge until just before Zas.