Where to place testimonials

Does anyone have any input on the following?

We're looking at adding in testimonials to a website for a client who provides building services. We were thinking of either putting them alongside the projects in his portfolio, on a "testimonials" page, or both.

Does anyone have any data on how effective either or all of these are together or alone? More importantly, has anyone seen any research that says whether people look at a testimonials page or prefer them inline or look for a separate page?

I appreciate for en ecommerce site selling a physical product then you'd need it inline with the the product but in this instance it's about a project carried out by a service provider. We wondered if anyone had found whether it differed or not.

Thanks in advance for any feedback.