Caldas de Reis takes its name from the thermal springs — caldas — that drew the Romans here. The springs still flow, though putting your feet in the public fountains is officially discouraged for hygiene reasons. After a long hot day of walking, you'll understand the temptation and why they had to post signs.
To see the springs and follow the camino, turn left after crossing the first bridge. The route passes through the old quarter before reaching another bridge, with the municipal albergue and the way out of town on the far side.
The Iglesia de Santo Tomas Becket is one of very few churches in Spain dedicated to the murdered Archbishop of Canterbury — and possibly the only one in Galicia. The palm trees surrounding it make a cooling rest spot in the afternoon.
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On the way out of town, it is once more along the N550 (which frankly will be the case frequently between here and Santiago). Leave it to your right at the first bend in the road.