Does 'Belvedere' mean the same as 'viewpoint'?

A "belvedere" is a structure which commands a scenic view, not the view itself. The word itself comes from the Italian for "beautiful view", but its English sense is limited to buildings and the like.

Merriam-Webster defines it:

: a structure (as a cupola or a summerhouse) designed to command a view

This M.C. Escher drawing entitled "Belvedere" is what comes to my mind when I think of the word:

Belvedere - A roofed structure, especially a small pavilion or tower on top of a building, situated so as to command a wide view.

It seems as though this may actually be a more accurate translation than "viewpoint". However, it depends on the definition of "miradouro". If a "muradouro" is typically a viewpoint with a roofed overhang situated on a building, then a "belvedere" could be exactly what you're looking for.

If not, then it could be a percularity in translation. I suggest comparing definitions of miradouro (in Spanish) and belvedere to see how accurately the two compare.

Per wiktionary, a belvedere is “A turret or other raised structure offering a pleasant view of the surrounding area”. An example of its use:

The most important thing, she reflected, as she stood on the balcony of the Mairie which formed a most useful belvedere over the town, was to make her appearance as commonplace and down at heel as possible [...] (1919, Ronald Firbank, Valmouth, Duckworth, hardback edition, p. 57)