One of them is Westminster Palace's Clock Tower, commonly known as "Big Ben".
Although, actually, "Big Ben" is a bell, not the clock. And, the official name of the bell is really the "Big Bell". To confuse even more, the "Clock Tower", which is where both the iconic clock and bells are located, had a name change several years ago to the "Elizabeth Tower" in honour of Queen Elizabeth's Diamond Jubilee.
Although, actually, "Big Ben" is a bell, not the clock. And, the official name of the bell is really the "Big Bell". To confuse even more, the "Clock Tower", which is where both the iconic clock and bells are located, had a name change several years ago to the "Elizabeth Tower" in honour of Queen Elizabeth's Diamond Jubilee.