The Hôtel du Lac is one of the strangest buildings in North Africa: an enormous inverted pyramid of poured concrete, 13 floors wide at the top and narrowing to near-nothing at the base, built in 1973 at the northern end of Avenue Bourguiba. It was designed by the Italian architect Raffaello Contigiani, and its sheer architectural audacity — a tower that widens as it rises, cantilevered over a garden of palm trees — was either visionary or delusional depending on your point of view.
The hotel closed in the 1990s and the building has stood empty ever since, slowly decaying into one of Tunis's most compelling pieces of urban furniture. It cannot be entered but is easily visible and worth a detour for anyone interested in Brutalist or bold modernist architecture. It sits at the junction of Avenue Bourguiba and Avenue Mohammed V, a ten-minute walk from the medina gate.