New York, NY —

The man who's led the Solomon R. Guggenheim Foundation for nearly 20 years has announced he's stepping down from his post as director.

Thomas Krens' time at the foundation has been marked by an effort to create a global presence for the Guggenheim and he leaves amid concerns about the direction the museum has taken.

We're joined on the phone now by arts writer Lee Rosenbaum who's followed Krens' tenure closely.