People visit the Hundertwasser House in Vienna, Austria, June 17, 2019. Hundertwasser House, an landmark building known for its colorful external walls and unique style, was designed by Austrian artist Friedenscreich Hundertwasser. It was constructed between 1983 and 1985. Up to now, it is still an apartment for ordinary residents and one of the most visited buildings in Vienna. (Xinhua/Guo Chen)