Ancient Roman Windows
In the main rooms of Roman private houses windows opened on the peristylum, and it seems likely that in private houses rooms situated on the first floor and used for domestic purposes didn't usually have windows that opened onto the street. On upper floors there were outside windows in those rooms which had no view of the peristylium, as in those above the rented rooms in the House of Pansa and in insulae generally.
Roman country houses might have outside windows in the first story. Some windows were provided with shutters, which were made to slide from side to side in a framework on the outside of the wall. These shutters were sometimes in two parts moving in opposite directions; when closed they were said to be iunctae. Other Roman windows were latticed; others again, were covered with a fine network to keep out mice and other pests.
Glass was known to the Romans of the Empire, but was too expensive for ordinary use in windows. Talc and other translucent materials were also used in window frames as a protection against cold, but only rarely.
Ancient Roman Windows.