Summary of Forms
There are particular rules for relations of place associated with the proper names of (i) cities and (ii) islands, as well as the words (iii) domus and (iv) rūs [the countryside]
- The place from which uses the ablative
- The place to which uses the accusative
- The place at which uses the locative
- no prepositions!
Again, this system of relations of place and case forms is distinct from the archetypes discussed in this earlier post.
———————————
Review of the Locative
In the first and second declensions (think Eurōpa and Ephesus), the locative is:
- identical to the genitive in the singular (Eurōpae, Ephesī)
- identical to the dative in the plural (Eurōpīs, Ephesīs)
In the third (and I assume fourth and fifth?) declension (think Carthāgō), the locative is:
- identical to the dative in singular and plural (Carthāginī or Carthāgine, Carthāginibus)
[note the the plural of all these examples are superfluous–plural datives only apply to place names that are already plural, such as Philippī –> Philippīs]
———————————
Place to Which (abl.)
He was absent from Rome: Rōmā abfuit.
He left home yesterday: prīdiē domō abiit.
Place from Which (acc.)
She arrived in Rome on the sixth day: Rōmam sextō diē vēnit.
I will go into the country: rūs ībō.
They will sail from Delos (abl.) to Rhodes (acc.): Dēlō Rhodum nāvigābunt.
Place at Which (loc.)
There are three hundred statues at Samos: Samī trecenta signa sunt.
The temple had been at Athens: Athēnīs aedem erat.
———————————
The Essential AG: 427
Famous Phrase : ūnus papa Rōmae, ūnus portus Ancōnae, ūna turris Crēmōnae, una ceres Rācōnae
(one pope in Rome, one port in Ancona, one tower in Cremona, one beer in Rakovnik)
[motto of the Rakovnik Brewery]
Ok, not so famous, and dripping with neo-Latinisms, but it’s got a lot of locatives!
Latin for Addicts 
Jenney’s First Year Latin (and I think Wheelock) says that 1st & 2nd singulars are like the genitive, and all others are like the ablative in whatever number is dictated by the word, which only makes a difference in the singulars.
Jenney does add that rus and the occasional 3rd have a locative in -i. He says the locative of Carthago is Carthagini. HOWEVER, this book does have a tendency to ignore alternate forms for the sake of not confusing students too much (the 79 edition says accusative plurals of 3rd i-stems is -es OR -is, the 90 edition says only -is; though the 90 edition is much inferior to the older one).
I’m going to look into this just as soon as I’m domi.