Most geographical names are changed in Latin, because a geographical name in Latin must be adapted to:
1. The Latin spelling and pronunciation.
2. The Latin conjugation system.
The town Skara in Sweden fits into the 1st declension, although its spelling is changed to "Scara".
When you speak about towns and cities in Latin, you don't need prepositions. The conjugation system is enough to express anything related to them.
Example: Skara is a town in Västergötland=Scara oppidum Westrogothiense est
He was born in Skara=Scarae natus est
We are going to Skara=Scaram imus
We are leaving Skara=Scarā imus