In the past four weeks the Soap Factory, as part of its Common Room series, has led some fascinating walking tours. Most recent was Invisible Minneapolis, which looked at development plans that never came to be. It was a compelling peek at what could have been in our city and left me both completely depressed and hopeful that good decisions can be made in the future. One of the Invisible Minneapolis stops was the largely vacant Block E, a multi-use retail/entertainment center that opened in 2004 and just eight short years later sits largely vacant. The four ground floor anchor…