Curiously enough, the Abbe Brasseur has argued for the probability of their invasions upon other (though I think insufficient) grounds (see his Informe acerca de las Ruinas de Mayapan y de Uxmal).
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "ruinas" in a variety of sentences. We hope that you will now be able to make sentences using this word.