I have two photos that I took while on vacation, one of the Public Market sign in Seattle and the other is the Sax hotel in Chicago. I have manipulated them in photoshop and am impressed with both photos. Is it legal for me to sell these photos?
Yes you can sell the photographs to whoever wants to buy them.
The problems are encountered when the images are used commercially in some design material or in an advertisment.If the building design is trademarked, such as the Sydney Opera House the buyer must be aware that it cannot be used commercially.
There is a lot of information on the iStock Photo website about what can be sold.