A stained-glass window (German, probably 16th-century) at Pena Palace, in Sintra, Portugal. It's labeled "<i>Kaiser Constantin das heilig kreutz und jerusalem bringend</i>" ("Emperor Constantine brings the True Cross and Jerusalem"); a depiction of the Emperor bringing the True Cross to the city of Constantinople.
Unknown author<span style="display: none;">Unknown author</span>
16th century?
<a rel="nofollow" class="external text" href="http://repositorio.ul.pt/handle/10451/4099">GASPAR, Nuno Miguel (2011). <i>Os vitrais do Palácio da Pena e a colecçao de D. Fernando II: contributos para o seu estudo</i>. Tese de mestrado, Arte, Património e Teoria do Restauro, Universidade de Lisboa, Faculdade de Letras</a>