The Identify Beat command lets you establish a tempo/meter map for audio that was recorded without a click, or for imported audio with unknown tempos.

The Identify Beat command analyzes a selection range (usually with a distinct number of beats or measures) and calculates its tempo based on the specified meter. In doing this, Bar|Beat Markers for the calculated tempo are inserted and appear in the Tempo ruler at the beginning and end of the selection; in addition, meter events are inserted into the Meter ruler.