Some here seem to think that Christianity ought to be the only religion that has the right to put their teachings on public property.
I personally would rather see religious expressions of many religions represented publicly than NONE.
I don't see it as clear at all, the Supreme Court gave conflicting findings and pushed the question you ask further down the road, but did nothing to settle the question of whether a community can put religious symbols on the public property in their community. (The statue of Brigham Young in Salt Lake City for example.)
The Constitutional ban of "establisnment of a religion" means the compelling of citizens to join a religion or suffer consequences of some kind from the government. Putting monuments in a public place should not require evidence that the monument was historical or art or anything else, it could in fact be a recognization that many people in the community adhere to certain beliefs.
To answer the question about Hindus or Islamics, or some other recognized religions monument, I would say it depends on whether the local community (and not some offended individual) wants or does not want the monument.