Heerlen (Dutch pronunciation: [ˈɦeːrlə(n)] ; Limburgish: Heële) is a city and a municipality in the southeast of the Netherlands. It is the fourth largest municipality in the province of Limburg. Heerlen forms part of Parkstad Limburg, formerly known as Oostelijke Mijnstreek (Eastern Coal Mining District), an agglomeration with about 220,000 inhabitants. After its early Roman beginnings and a modest medieval period, Heerlen became a centre for the coal mining industry in the Netherlands in the late 19th century. In the 20th century, architect Frits Peutz played a major role in shaping the city as we know it today. His most famous design, and a distinctive building in the city centre, is the so-called Glaspaleis (Glass Palace), listed as one of the world's thousand most architecturally important buildings of the 20th century. Wikipedia
This warm abode of Heerlen is a delightful place to visit in Netherlands. A gripping city on its own right, Rotterdam also deserves a visit. Add Rotterdam to your vacation plan, it has an interesting bunch of activities to do on your visit like Market Hall, Diergaarde Blijdorp, Erasmusbrug. Also, to reach Heerlen, you'll have to take a flight to Rotterdam; so its not really a detour. And even if it is, the city is worth paying at least a quick visit. A vacation to Heerlen can typically be of 1-2 days. Immerse in the spirit of the city and you'll not miss your home.
Heerlen is an affair to remember, follow this apt itinerary of the place and return home with a bunch of memories.