A very tall building with a clock on each of it's sides.
 Clock tower in a busy big city with green roofa
A big clock tower topped with a walk and an American flag, stands tall against a blue sky, far ahead of city skyline, and right above a lot of teal-roofed domiciles.  
A clock tower stands high above the rooftops, in the blue sky.
a clock tower with a weather vane on top rises high into the sky