The Polish 4G spectrum auction was a significant event for the country's telecommunications market. It was the first time spectrum was awarded through an auction process. The auction lasted 8 months and raised over PLN 9 billion. However, due to a flawed auction design, the process was prolonged and required government intervention to conclude. The paper details the auction rules, bidding behavior, and outcomes, providing valuable lessons for policymakers in Poland and other countries on how to design successful auctions.