Hmm, a good resource on this topic would be Peter Murray's The Architecture of the Italian Renaissance. To give a very brief overview, what people usually talk about with respect to Renaissance architecture somewhat imprecisely is the revival of Classical forms and its application to the built environment of Renaissance Italy. This on one level extended to the use of classical motifs(for example, using columns instead of piers to support buildings) and on another to changes in the formal arrangement of buildings(for example, changes in the layout of buildings) but applied to the needs of Renaissance Italy-for instance, the need to build churches on the basilican plan or some variant therof and to produce large courtyarded urban palaces or-later-large country villas. To provide one concrete example, here is one especially famous Renaissance building, the Pazzi Chapel. You can observe many of the features I have mentioned here, such as the use of classical architectural motifs, the extensive use of the round arch and the dome, and so on. That said, Renaissance architecture changed a lot over the course of its development and there's a lot that could be said about its development. Are you trying to research some specific aspect of Renaissance architecture, e.g. changes in garden design, or in urban planning, or changes in the development of the country villa?