What part of speech is there when it begins the sentence?

It is generally an adverb when located at the beginning of a sentence. You should find that it modifies the verb that follows it, as to where. However, it could be a pronoun if it represents a thing or things.

adv.

>At or in that place: "Sit over there." "There she goes." "There's the parking lot!"

>To, into, or toward that place: "I wouldn't go there again. "

>At that stage, moment, or point: "Stop there before you make any more mistakes."

>In that matter: "I can't agree with him there."

pron.

>Used to introduce a clause or sentence: "There are numerous items." "There must be another exit."

>Used to indicate an unspecified person in direct address: "Hello there!"

adj.

>Used especially for emphasis after the demonstrative pronoun that or those, or after a noun modified by the demonstrative adjective that or those: "That person there ought to know the directions to town. "

>Nonstandard/Slang (generally in the Southern U.S.) - Used for emphasis between a demonstrative adjective meaning "that" or "those", and a noun: "No one is sitting at that there table." "Them there beans ought to be picked."

n.

>That place or point: "It stopped and went on from there."

Compliments of www.manuscriptex.com