As far as ancient architecture goes, I'd have to agree that Angkor Wat is pretty special. I also love Machu Picchu and all the Mayan and Aztec pyramids (don't know the names of any of them!)
I also love anything by Gaudi, particularly Sagrada Familia. His buildings are magical.
The Bank of China Tower in Hong Kong and the Chrysler Building are my favourite high-rises. The Bank of China Tower is such a striking building, particularly at night and the Chrysler Building is the most beautiful highrise building in the world.
Closer to home, I've always liked the Three Graces in Liverpool, particularly the Liver Building (I've always loved the statues of the Liver birds on top of the clock towers!)
I really like all the bridges in Newcastle. The Tyne Bridge has loads of character and the Millennium Bridge is amazing.
I also love the Brighton Grand Hotel - such a classy and elegant building.
In my home city of London, I love the brutal and uncompromising Lloyds Building, probably one of the most unique buildings in the world.
I also love the Natural History Museum. I love the colour scheme, the yellow bricks look almost golden. I love the entrance with it's iconic archway and I love all the gargoyles perched on the roof, all the weird looking animals and creatures. It's definitely one of my favourite buildings in the world.