Helpoort, or Hell's Gate, is the oldest city gate in the country. It got its name due to the fact that prisoners were kept in its tower. Construction of the gate, commissioned by Henry I, began in 1229; it is a part of the First City Walls and served as the southeastern entrance to the city. When the Second City Walls were constructed in the 15th century, the gate was no longer needed as an entrance to the city. Over the years, it served as a residence, storage space and workshop. Today the gate houses a museum dedicated to the history of Maastricht's fortifications.