What is the difference between an overmantel and a pier glass?

An overmantel mirror is specifically constructed in a landscape or tall arched format to occupy the wide wall space directly above a fireplace. Their proportions match the width of standard chimney breasts. Pier glasses are traditionally taller and narrower, designed to hang on the narrow pier of wall space situated between two windows.

How should I clean antique mirror glass and gilt frames?

Dust the carved gesso and giltwood gently with a dry, soft brush to remove surface particles without damaging the delicate gold leaf. Moisture can lift old gesso, so liquid cleaners must be avoided on the frame entirely. Use a minimal amount of distilled water on a soft cloth for the glass itself, taking care not to let any liquid seep behind the edges where it might affect the old silvering.

Can these mirrors be placed on a wall without a fireplace?

While designed for the hearth, many examples function successfully as large wall mirrors in hallways, dining rooms, or living spaces. Their architectural framing allows them to act as standalone statement pieces. When hung independently, ensure the wall structure can bear the considerable weight of the timber, gesso, and glass construction.