Look! House Numbers in the Window

We love the variety and sometimes quirkiness of the house numbers on the buildings in our neighborhood. Many are hand-painted onto decorative tiles or cast into bronze plates. Others are printed on a lamp or transom over the front door. But it's these modest numbers perched on a window sill that really won us over...

This seems like a temporary solution, as there's nothing anchoring the numbers to the house. However, these look like they've been there a while. Makes us wonder - was it planned? Forgotten. Last thing on a long to-do list?