Если перед неисчисляемым вещественным существительным стоит прилагательное, то перед прилагательным ставится неопределённый артикль? если да, объясните почему.

1: hi! where were you at previous week?

2: hey! i've just returned from an amazing trip to london.

1: oh, i really like this city. i was there when i was 10. so, which landmarks have you visited?

2: there were a lot of different places i wanted to visit, but unfortunately i had only one week, so i visited a part of landmarks.

1: have you visited westminser abbey?

2: yes, i took a lot of photos there. i also looked at big ben which is near to the abbey.

1: i think big ben is one of the most popular sights in london. but there is also the london

2: a trip on the london eye was really amazing! it's so high, about 45 metres, but i wasn't afraid, i was excited. i saw all london!

1: i know that there are excoursions on the river thames.

2: yes, i took one. it was interesting, we saw tower bridge, london bridge and a lot of other bridges. they are very beautiful.

1: so, do you think your trip was wonderful?

2: yeah it was really cool. 

1: let's go to paris next weekends? i've always wanted to visit disneyland!

2: oh, ok, it good idea!

1: ok, meet tomorrow.

2: bye!