Complete the time traveler's Yelp review of a 19th-century establishment.

I highly recommend the little cafe in 1890s Paris _____ I accidentally left my modern smartphone!

The correct answer is where.

We use the relative adverb where to refer to a place (the cafe). It means the same thing as in which or at which.

If you wanted to use "which" or "that" in this sentence, you would need to add a preposition: "...which I accidentally left my modern smartphone in!" Because the preposition is missing, "where" is the only correct choice.