▁uno fficial ly ▁enc ro ached , ▁but ▁officially ▁miss ions ▁maintained ▁authority ▁over ▁native ▁ne oph y tes ▁and ▁control ▁of ▁land ▁hold ings ▁until ▁the ▁ 1 8 3 0 s . ▁At ▁the ▁peak ▁of ▁its ▁development ▁in ▁ 1 8 3 2 , ▁the ▁coast al ▁mission ▁system ▁controlled ▁an ▁area ▁equal ▁to ▁approximately ▁one - six th ▁of ▁Al ta ▁California . ▁The ▁Al ta ▁California ▁government ▁sec ular ized ▁the ▁miss ions ▁after ▁the ▁passage ▁of ▁the ▁Mexican ▁sec ular ization ▁act ▁of ▁ 1 8 3 3 . ▁This ▁divided ▁the ▁mission ▁lands ▁into ▁land ▁gr ants , ▁in ▁effect ▁legit im izing ▁and ▁comple ting ▁the ▁transfer ▁of ▁Indian ▁con greg ation ▁lands ▁to ▁military ▁command ers ▁and ▁their ▁most ▁loyal ▁men ; ▁these ▁became ▁many ▁of ▁the ▁R anch os ▁of ▁California . ▁ ▁The ▁surv iving ▁mission ▁buildings ▁are ▁the ▁state ' s ▁oldest ▁structures ▁and ▁its ▁most - vis ited ▁historic ▁monuments . ▁They ▁have ▁become ▁a ▁symbol ▁of ▁California , ▁appearing ▁in ▁many ▁mov ies ▁and ▁television ▁shows , ▁and ▁are ▁an ▁insp iration ▁for ▁Mission ▁Rev ival ▁architecture . ▁The ▁oldest ▁cities ▁of ▁California ▁formed ▁around ▁or ▁near ▁Spanish ▁miss ions , ▁including ▁the ▁four ▁largest : ▁Los ▁Angeles , ▁San ▁Diego , ▁San ▁Jose , ▁and ▁San ▁Francisco . ▁ ▁Al ta ▁California ▁mission ▁planning , ▁structure ▁and ▁culture ▁ ▁Coast al ▁mission ▁chain , ▁planning ▁and ▁over view ▁▁ ▁Prior ▁to ▁ 1 7 5 4 , ▁gr