Union is the kind of bar that Bochum does well: no pretension, proper draught beer, and a mix of students and older regulars who have been drinking here for years. Altbier from the Ruhr is the thing to order. The interior is dark-panelled and comfortable in an unpretentious way, and it stays lively until late on weekends without becoming unpleasant.
It gets crowded on Thursday and Friday nights — arrive before 9pm if you want a seat. Cash preferred; card payment sometimes works but the connection is unreliable.