The answers are worldwide landmarks.
12) Shawl unpicked with land and air (8, 4)
14) I'd ride cars for this (5, 5)
15) Z game with no beginning (5)
16) Cricket equipment linked to a party (6, 5)
18) Nuclear research centre and a quarter film (5, 5)
25) Endless material to inter Harry (7, 4)
Many thanks.
If anyone's interested in more clues, here they are.
19) Our Lady in Avignon (5, 4)
24) Law for WW2 ship lacking time (6, 2, 7)
27) Keep made from a drink in retrospect (5, 2, 4)
30) 1 of 5 birds that flew with an explorer (7, 4)