According to Genesis, Noah opened a window before sending out a raven.
Genesis 8:6 says that after forty days Noah opened the window of the Ark that he had made. He then sent out a raven, followed by repeated releases of a dove. The window is therefore part of the sequence that tests whether the Flood waters have receded.
This question concerns the architectural feature, not the birds themselves. The passage later describes Noah removing the covering of the Ark and seeing that the ground was drying, but the first opening named in this sequence is a window.
English translations vary slightly in how they render the Hebrew term, with “window,” “opening,” or related wording appearing in some versions. The standard English answer remains “a window,” and Genesis places it in the upper part of the Ark narrative before the bird tests.