Heroica Nogales, in the Mexican state of Sonora. It is just across the border to Nogales, AZ.
There are many cities that not only are at an international border, but are actually on both sides of the border. For example, Gorizia (Italy) and Nova Gorica (Slovenia).
I guess you mean where is Nogales, Sonora, Mexico. Nogales is a city and its surrounding municipality on the northern border of the Mexican State of Sonora. The municipality covers an area of 1,675 square kilometers (647 sq mi), and borders to the north the city of Nogales, Arizona, United States, across the US-Mexico border. Its coordinates are: 31°19'N 110°57'W It is about 1 hour south of the Tucson AZ Airport.
There are several cities directly on the border. Ciudad Juarez, Tijuana, and Nogales come to mind. In particular there are two joined towns called Nogales, one in the U.S state of Arizona and the other in the Mexican state of Sonora.
"Nogales" means "walnuts" in English. It can also refer to a city in Arizona bordering Mexico.
There are several of them, right at the U.S.-Mexico border, such as San Ysidro, Calexico, El Paso and Brownsville.
Nuevo Laredo, at the other side of the border from Laredo, TX.
All along western Mexico, from the Sonora-Arizona border between Nogales and Douglas, AZ, down the Mexican Pacific Coast close to the city of Puerto Vallarta.
The southernmost city (and thus the closest city to the equator) in Mexico is Tapachula, Chiapas.
That would be Calexico, a small town about three miles from the Mexican border.
The city in Alabama closest to the Florida border is Flomaton. It is located in the southern part of Alabama and shares a border with Florida.
The city close to the border is called San Luis Rio Colorado, close to the border to Yuma, AZ.
Munich is the major city that is nearest to the Austrian border.