Complex sentence: So far, two construction stages have been identified at the site, but according to Andrews' survey in 1966, the lack of significant differences in the architecture of buildings indicate that they were built within a relatively short period of time.
Split into simpler sentences: So far, two construction stages have been identified at the site. After conducting his 1966 survey, Andrews concluded that the lack of significant differences in architectural style between of buildings indicated that they were built within a relatively short period of time.