Here is a piece of useful advice when trying to find the NEW Pilgrim Office / Oficina del Peregrinos.
The local concello / city council, for political reasons I will not discuss here, replaced the former glass, engraved directional signs for "Oficina del Peregrino" all over the city, with signs in GALLEGO (Galician) and NOT standard Spanish that indicates directions to the "International Center to Welcome Pilgrims." To someone who does not already know where they are going, Rua Carretas 33, Santiago de Compostela, you can EASILY get lost. During my month there this summer, I spent many hours at the bottom of the ramp from Plaza de Obradoiro directing arriving pilgrims to the office, 100 meters down the street on the left.
The obscure wording of the directional signs was intentional, and exactly parallels the official designation of the renovated building at that address, NOT the specific function, simply as the Pilgrim Office. There are other, pilgrim and Camino related offices sharing the very large building. The renovation costs were funded jointly by the Province of Galicia, the Cathedral Foundation, and grants from the EU.
The city of Santiago did not factor into the renovation to the best of my knowledge. Knowing Spanish politics, IMHO, logic rarely factors into practical decisions. You can connect those dots...
Because the specific spelling in Gallego cannot be duplicated using either the BING or Google Translate engines, I will not attempt to put it here. BUT, I will tell you that Google Maps WILL NOT show the International Welcome Center for Pilgrims or any variant thereof.
However, Google and Bing Maps DO provide the location of the Pilgrim Office / Oficina del Peregrino, Santiago de Compostela.
When using street signs for naivagtion, just follow sign any that contains the word "Oficina" AND "Peregrino." If using Google Maps, use "Pilgrim Office."
As another, related fact, arriving pilgrims will find a conveniently located Correos (post office), ALSA bus agent, a RENFE ticket agent, and even a Province of Galicia tourism information office on site or immediately adjacent to the Pilgrim Office. What they will NOT find is a TI for the city of Santiago. In fact, the (superior IMHO) TI for the city remains at Rua do Vilar 63, on the other side of the Cathedral, where it has been for some time. Draw your own conclusions, but IMHO, there is a political difference of opinion that caused a gap in service-delivery. The arriving pilgrims are caught in the middle. Just be prepared.
I hope this helps.