In LLPSI’s companion, Colloquia Personarum, the fifth story uses a construct I don’t understand.
In oppido Tusculo magnum forum est.
Which seems clear as "In the town of Tusculum is a large forum."
But later, the adjective Tusculanus, -a, -um is introduced.
So, in the former, why is Tusculum in the ablative here? My understanding of the locative is weak, but it seems this would be a situation where it would be used, so ought to be In oppido Tusculi .... Or instead use the adjective, such as In oppido Tusculano ....
In oppido Tusculo magnum forum est.
Which seems clear as "In the town of Tusculum is a large forum."
But later, the adjective Tusculanus, -a, -um is introduced.
So, in the former, why is Tusculum in the ablative here? My understanding of the locative is weak, but it seems this would be a situation where it would be used, so ought to be In oppido Tusculi .... Or instead use the adjective, such as In oppido Tusculano ....