Cast your eyes upon something, figuratively or literally. Synonymous with take a look. Both forms are found in both British and U.S. English throughout the twentieth century but the charts below, from Google Ngram, showing frequency of use of have (blue line) and take (red) between 1940 and 2008, suggest some of the nuances. In Britain, below, have started the period way in front, then steadily declined until it was overtaken by take in the mid-90s.
In the U.S., the two were roughly equal until about 1960, when take took off and have went into a tailspin, only to revive recently as a NOOB:
Are these clothes worth it? Go have a look. If ever there was a season to explore the mind of high fashion, this is it. (William Norwich, New York Times, January 18, 2004)/Mitt Romney has turned black, at least according to a graphic that appeared on a Fox News program today. Have a look — this is strange even by the standards of this Republican race. (Erik Wemple, Washingtonpost.com, December 14, 2011)