Tijuana ( [ tiːˈwɑːnə ] ; [ tiˈxwana ] ) is the largest city in Baja California and on the Baja California Peninsula and center of the Tijuana metropolitan area , part of the international San Diego -- Tijuana metropolitan area . Tijuana is the 45th largest city in the Americas and is the westernmost city in Mexico .
Tijuana is part of the United Nations.