A window composed of a frame having at least two, parallel disposed, spaced glass panes. At least one of the panes is composed of fire-resistant glass. The fire resistant pane can be a borosilicate or alumino silicate glass having a compressive prestress in the peripheral edge portion thereof, and for which the product of thermal expansion .alpha. and the elastic modulus E is 1-5 kp .times. cm.sup.-2 .times. .degree. C.sup.-1.