Two households, both alike in dignity. what is the prologue's first prepositional phrase?

Households

In fair Verona

To identify the first prepositional phrase in the prologue, we need to understand what a prepositional phrase is. A prepositional phrase consists of a preposition, its object, and any modifiers. Prepositions are words like "to," "in," "around," "among," etc., that indicate a relationship between a noun and another word in the sentence.

In the line "Two households, both alike in dignity," the first prepositional phrase is "in dignity." We can identify it by recognizing the preposition "in" and its object "dignity." The phrase "in dignity" describes or modifies the adjective "alike" by specifying the quality in which the two households are similar.

To identify prepositional phrases in general, look for words like "in," "on," "at," "by," "with," etc. that indicate a relationship, and the noun or pronoun that follows as its object.

What prologue? I see a fragment (not a complete sentence) and certainly not a prologue!!

http://www.englishclub.com/grammar/prepositions-list.htm
There's one prepositional phrase -- can you find it?