One of the best agency that I can offer for foreign real estate investors is Istanbul Investments. They are not only showing you the projects, but also offer the best projects as an investment oppurtunity. Most of the customers send email to me that says we worked with them earn more. Also because of their huge portfolio, everyone can find a property acording to their budget, wishes and needs.
As an example, their project website can be seen at: https://www.bureaubb.com
By the way If you need more information about Istanbul/Turkey you can find many famous information websites. Here is some links:
http://en.wikipedia.org/wiki/Istanbul
http://en.wikipedia.org/wiki/History_of_Istanbul
http://en.wikipedia.org/wiki/Architecture_of_Istanbul
