Abstract: A method for selecting an advertisement (ad) to display in an ad spot, comprising: accessing a database documenting categories, each including at least one event item having geographical coordinates, an event occurrence time parameter and at least one descriptive parameter; receiving at least one theme definition selected for an advertising campaign; matching between the theme definition and at least one relevant category from the categories; assigning an ad from the advertising campaign to the relevant category according to the matching; receiving a message indicative of a location of a user at a specific time from a client terminal associated with the user; finding an event item corresponding to the location and time; selecting an ad from the relevant category which includes the corresponding event item; and sending the client terminal a response to the message, comprising instructions to present the ad on a display of the client terminal.