Mishnayos Shekalim Perek 8 Mishnah 4

With regard to a curtain that became ritually impure from a secondary source of impurity, since its ritual impurity is by rabbinic law and not Torah law, there is no need to remove it from the Temple. Rather, it is immersed inside the Temple. And if it were removed to outside the courtyard in order to immerse it, it can be brought back into the courtyard immediately. Since it is ritually impure only by rabbinic law, there is no need to wait until sunset before returning it. But if it became impure from a primary source of impurity, e.g., it came into contact with the carcass of one of the eight creeping animals that confer impurity by Torah law, it is immersed outside the courtyard and is spread out to dry on the rampart. This is the low wall surrounding the Temple courtyard and the buildings within it, which has a lower level of holiness than the courtyard. The reason for this policy is because the sun needs to set on it. Immersion does not confer ritual purity on an item that became impure by Torah law until after the sun has set. And if this curtain were new, it is spread out to dry on top of the bench [itztabba], a prominent place on the Temple Mount, so that the people will see its craftsmanship and perceive its beauty.

פָּרֹכֶת שֶׁנִּטְמֵאת בִּוְלַד הַטֻמְאָה, מַטְבִּילִין אוֹתָהּ בִּפְנִים וּמַכְנִיסִין אוֹתָהּ מִיָּד. וְאֶת שֶׁנִּטְמֵאת בְּאַב הַטֻמְאָה, מַטְבִּילִין אוֹתָהּ בַּחוּץ וְשׁוֹטְחִין אוֹתָהּ בַּחֵיל. וְאִם הָיְתָה חֲדָשָׁה, שׁוֹטְחִין אוֹתָהּ עַל גַּג הָאִצְטַבָּא, כְּדֵי שֶׁיִּרְאוּ הָעָם אֶת מְלַאכְתָּהּ שֶׁהִיא נָאָה: