The chapter house has an original mid-13th-century tiled pavement. A door within the vestibule dates from around 1050 and is believed to be the oldest in England.[citation needed] The exterior includes flying buttresses added in the 14th century and a leaded tent-lantern roof on an iron frame designed by Scott. The Chapter house was originally used in the 13th century by Benedictine monks for daily meetings. It later became a meeting place of the King's Great Council and the Commons, predecessors of Parliament.
A window in the vestible dates back to when? (If the question is unanswerable, say "unanswerable")
unanswerable