Adobé: a brick made out of hay, clay, mud and animal manure.
Alta California: Northern California. Baja California was South.
Arch: a
upside down "u" used in the corridors. 
Atole: Atole is a creamy mush made of wheat. (like cream of wheat)
Campanario:
A structure that the bells are in (not a bell tower).
Citizens: A citizen is someone who is native to that country or has become one by fillng out many papers.
Colonize: To colonize is to start a settlement.
El Camino Real: El Camino Real is the road that runs through all of the missions. It took one day to walk from mission to mission.
Mission: A small settlement made by padres to Christianize and to colonize.
Neophytes: A Native American who was Christianized.
New Spain: What we call Mexico.
Padre: Someone from Spain who was on a mission to christianize Indians.
Presidio: A presidio is a type of fort.
Rancho: A rancho is a piece of land given by the Spanish government.