Most navy blue curtains come in pairs with costs of $15-$300. Basic, but still effective, curtains usually cost less than $30, but be cautious — this price range may only include one curtain.

Floor-to-ceiling curtains carve up the interior of this open-plan apartment in Bilbao, Spain, which has been overhauled by architecture studio Azab. Called Ready-made Home, the project is set ...