Bow your head, say a prayer and perhaps even light a candle in San Juan Cathedral. This majestic religious building may not be open all day, so check ahead for hours if you'd like to go inside.
You'll be spoiled for sightseeing choice when in San Juan. San Juan Cathedral is a good place to begin here, but there are loads of other worthwhile places to experience. Museo del Vino Bodega Graffigna, Rio San Juan, and Plaza 25 de Mayo are close to the principal church and will round out your day nicely.