"There" as an adverb

Question

In sentences like, "there is a great place down the street," and "there is no reason to do that," there is being used as an adverb, and OED defines this particular usage as:

ADVERB
(usually there is/are) Used to indicate the fact or existence of something:
there’s a restaurant round the corner
there comes a point where you give up

My question is, what exactly is it modifying?

Also, if it's modifying is/are, then doesn't is indicate the fact of existence well enough on its own?

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Edit: Is it just a kind of there-support to avoid writing a sentence like, " a restaurant around the corner is"?

Answer 1

It is not an adverb, nor a locative of any sort, but a 'dummy' pronoun, without reference. Its sole function is to act as the subject of a sentence asserting the existence of the 'complement' of the verb BE - as you suggest, it is the idiomatic way of expressing "A restaurant around the corner is".