A mountain hut is a building located high in the mountains, generally accessible only by foot, intended to provide food and shelter to mountaineers, climbers and hikers. Mountain huts are usually operated by an Alpine Club or some organization dedicated to hiking or mountain recreation. They are known by many names, including alpine hut, mountain shelter, mountain refuge, mountain lodge, and mountain hostel. It may also be called a refuge hut, although these occur in lowland areas (e.g. lowland forests) too. Mountain huts can provide a range of services, starting with shelter and simple sleeping berths. Some, particularly in remote areas, are not staffed, but others have staff which prepare meals and drinks and can provide other services, including providing lectures and selling clothing and small items. Mountain huts usually allow anybody to access their facilities, although some require reservations. While shelters have long existed in mountains, modern hut systems date back to the mid-19th century. The Swiss Alpine Club has built huts since 1863. In the United States, the Appalachian Mountain Club built its first hut at Madison Spring in New Hampshire in 1889. The construction of refuges and shelters in the Alps date back to ancient times, when Roman roads led across the mountain passes. In the High Middle Ages, hospitales were erected along the trade routes; cottages and sheds on the high mountain pastures served for Alpine transhumance. The long history of mountaineering from the 19th century onwards has led to a large number of Alpine club huts as well as private huts along the mountaineering paths. These huts are categorised according to their location and facilities. They may have beds or a mattress room (Matratzenlager) for overnight stays. Just as the Margherita Hut in the Valais Alps is the highest alpine refuge at 4,554 m, the Rifugio Mario Premuda in Trieste owned by the Italian Alpine Association is the lowest refuge in the Alps at 82 m.