Is the entrance of Niagara contains Tamil wordvaanga vaanga?

The phrase "vaanga vaanga" is a Tamil expression meaning "come, come". While it's a common phrase in Tamil, it's highly unlikely to be found at the entrance of Niagara Falls.

Niagara Falls is a natural wonder located on the border of the United States and Canada, and its tourism infrastructure is primarily in English and French.

It's possible you may have seen this phrase somewhere else and associated it with Niagara Falls, but it's not a common or official part of the area's language or signage.