1. A method performed by data processing apparatus, the method comprising: receiving data identifying a physical location; obtaining data identifying a plurality of events occurring in the physical location during a particular time period; computing a respective plurality of signal scores for each of the events, wherein computing the respective plurality of signal scores for each of the events comprises: obtaining search results for a search query that includes a first term identifying the physical location and a second term indicating an interest in events occurring in the physical location; determining a position in a ranking of the search results of a highest-ranked search result that mentions the event; determining a frequency with which the event is mentioned in resources identified by the search results; and using the position of the highest-ranked search result and the frequency with which the event is mentioned in resources identified by the search results to compute a first signal score of the plurality of signal scores for the event; computing a respective popularity score for each of the plurality of events by combining the respective plurality of signal scores for the event; and generating a ranking of events occurring in the physical location during the particular time period based at least in part on the popularity scores.