Luxembourg is a developed country, with an advanced economy and one of the world's highest GDP (PPP) per capita. The City of Luxembourg, with its old quarters and fortifications, was declared a UNESCO World Heritage Site in 1994 due to the exceptional preservation of the vast fortifications and the old city. Where to go: Clervaux. The pretty town of Clervaux in northern Luxembourg looks like a scene straight from a fairytale: a cluster of white buildings nestle among the hills and pointed towers rise into the sky. Ettelbruck. Diekirch. Larochette. Esch-sur-Sûre. Vianden. Echternach. Mamer.