NEW DELHI, India — Recently, residents of India's bustling capital have found large and often strange-looking objects along their daily paths: a giant steel bucket mounted on a wooden stand, a tree hanging from a crane, a gasoline can made of white tiles, and stretched nylon resembling the long wing of a bird caught between buildings.

"They say this is art, but I do not see anything special in a bucket," said Virendra Singh, a stocky policeman on guard near the steel bucket, the creation of celebrated contemporary artist Subodh Gupta. "We all have one in our bathrooms to store water."

Then he turned to look at the exhibit again. "But this is indeed a very, very big bucket," he said. "Maybe there is something more to it."

A volunteer unraveled the mystery. "This is going to be the most valuable vessel of the future because our city is running out of water," he told Singh. "The artist is telling the city to conserve water."

Singh was one of many New Delhi residents who experienced contemporary public art for the first time, thanks to a festival that has not only raised questions about accepted definitions of art, but also highlighted the challenges in preserving India's ecological heritage amid rapid urban development.

About 25 artists spread their larger-than-life art installations across the city's 16th-century quarters, shopping arcades, parks, business districts and traffic roundabouts. The installations were along sites located on a grid created for the city's latest object of pride: the gleaming new Metro rail, which in the past five years has become a potent symbol of the choked capital's efforts to transform itself for the 21st century.

"Public space is shrinking in this city, and we are trying to reclaim and re-engage with it through art," said Pooja Sood, curator of the public art extravaganza. "We broke through prevailing social, cultural and political barriers to bring contemporary art out of the elitist, white-cube galleries."

In the past decade, New Delhi has witnessed an unprecedented boom in the construction of high-rises, overpasses, malls and multiplexes at the expense of countless trees and old buildings. Conspicuous consumption and changing lifestyles are depleting the city's underground water supply and slowly edging the once-sacred Yamuna River out of people's consciousness.

"The installations ask a question, 'Where are you in this debate about environment versus progress?' And many people have looked at the installations and asked, 'Is this art?' " Sood said. "This is the beginning of a conversation between art and the city."

The art went up as the city was debating the fallout of the deadly attacks in Mumbai last month. After a series of bomb scares, security at the displays was doubled.

On a busy street near one site, a ricksha driver stared at the installation of a crane lifting a whole tree.

"That is like my life in this city. I feel uprooted," he said.

His friend said: "The terrorists are making us dance like that. We are hanging in the air because of them."