By Jenny Peters This is Concierge Confidential, a series in which we learn about a city’s best-kept secrets from people who specialize in exactly that: long-serving concierges from the best hotels in town. The Pfister Hotel opened in 1893 and remains a Milwaukee gem. With an ornate lobby and huge Victorian art collection, it’s an excellent HQ for exploring the city. As the Pfister’s Chef Concierge (so-called because “chef” is French for head concierge), Briana Greer oversees a team of Milwaukee experts, on hand to give visitors all the inside skinny on everything that the city has to offer. A …