Ten years have passed since Cheonggyecheon Stream was restored in the heart Seoul, becoming a tourist hot spot, but questions linger over its ecological and historical significance.

Some 190 million Koreans and tourists are estimated to have visited the stream since its restoration by former President Lee Myung-back on Oct. 1, 2005. The number is expected to exceed 200 million by early next year.

The restoration work for the stream began in July 2003, costing some 386.7 billion won ($328.9 million) and about 694,000 workforce. Through the restoration, citizens can walk along the 5.8-kilometer waterway, which has 22 bridges.

Some question the significance of the stream, which costs an average of 7.5 billion won a year to maintain the water level. Heavy rain has also caused mass die-outs of fish, prompting critics to question the stream’s ecological capacity.