When talking about going to a local bar one person says:

"Let's go to 1020!"

The other says:

"Let's go to the 1020!"

The first statement without an article seems correct. Yet by comparison:

"Let's go to supermarket" and "Let's go to the supermarket", it appears the second with an article is now correct.

What rule is at work here?

When talking about going to a local bar one person says, "Let's go to 1020!"
The other says, "Let's go to the 1020!"

The first statement without an article seems correct. Yet, by comparison, "Let's go to the supermarket" seems correct, while "Let's go to supermarket" doesn't seem correct.

What rule is at work here?