Kalorme in the Third Age

I always assumed Valinor was still physically on the Earth, but was in another dimension, or just hidden magically ie: beings could only come to Valinor if the Valar allowed it, and it was magically sealed against men. An analogy would be the western door of Moria, that has certain requirements to be fulfilled before it will open. In Valinors case, the requirements are the seeker must be an Elf, or otherwise have special permission, as in the case of Frodo and Gimli.