An onion dome is a dome with the appearance of an onion. These domes are frequently greater in diameter than the tholobate on which they rest, and their height generally surpasses their breadth. These bulbous formations taper to a tip smoothly. Many massive Mughal domes were also double-shelled, following the Iranian style. The Tomb of Humayun's architecture, notably its double-shelled dome, implies that its builders were acquainted with Timurid structures in Samarqand. The Taj Mahal's central dome has a bulbous appearance and a double-shelled structure as well.