1) Arena tops 2) Arena tops, sometimes 3) Ballgame rain checks 4) Bubbletops 5) Buckminster Fuller structures 6) Byzantine Empire structures 7) Capitol caps 8) Capitol toppers 9) Cathedral tops 10) Common state capital features 11) Crowns of furnaces 12) Cupolas 13) Features of some stadiums 14) Gable alternatives 1) Cupolas 
Remnant of a volcano that has a bowl shape formation