WORCESTER – People returning to work Tuesday after the long Columbus Day weekend and parking on Federal Street will be excused if they linger a bit to gaze at the latest Pow! Wow! Worcester mural on the Hanover Theatre for the Performing Arts building.

Over the weekend, 26-year-old mural artist Stathis Tsavalias (who goes by the moniker “Insane51”) was putting the finishing touches on his impressive 125-foot-by 50-foot mural that covers the Federal Street side of the building.

Mr. Tsavalias was one of 28 artists in this year’s Pow! Wow! Worcester festival from Aug. 31 through Sept. 9, said Jessica Walsh, co-director of the festival and owner of Worcester Wares at the DCU Center. He came back last week to finish it, she said.

“He has such a large wall that we knew that he was going to come back to finish it,” Ms. Walsh said. “Essentially, his murals have such technical details to them that it takes a little bit longer, especially on such a large wall.”

Based in Athens, Greece, Mr. Tsavalias’ specialties are realism and photo-realistic portraits combined with 3-D and illusion effects.

Using red and blue spray paint and with the aid of an electric scissor lift, Mr. Tsavalias, who studied at the Athens School of Fine Arts and started as a graffiti artist in 2007, has created a double-imaged piece.

After 515 cans of spray paint and 86 gallons of house paint (used to prime the wall before the artist arrived), the mural was done.

As seen by the naked eye, it’s a close-up of a couple in a loving embrace, but you see the beauty of the relationship is more than skin deep by seeing flesh and bone simultaneously.

If that wasn’t enough, with a pair of cardboard 3-D glasses, if you close one eye and look through the blue lens, you will see only the fleshy exterior of the couple, and through the red lens, you will see only the lovers’ bony interior.

"The technique is not used by many artists," Ms. Walsh said. "Some have started after Insane, but the style and technique is different and they do not use the glasses for an interactive experience. It is the only mural in the city that uses effects and 3-D."

Ms. Walsh said festival personnel research the artists ahead of time but give them very few restrictions.

“We give them general guidelines of no violence, no intolerance, nothing sexual or drug related. We tell them, this is our city. Be respectful and don’t mess this up for us,” Ms. Walsh said. “We don’t believe in telling artists what to paint, and there’s a trust relationship there. It’s known. You’re not going to do something that is going to upset everybody.”

Ms. Walsh said they knew they wanted to put something dramatic on the Hanover and the Hanover wanted the same.

“The mural doesn’t play safe in any way. It makes a statement. You can’t look away,” Ms. Walsh said. “I think it’s representative of what is going on in Worcester right now. I think people should keep their eye on Worcester. There are interesting things happening in Worcester.”

Mr. Tsavalias' work is the last of the Pow! Wow! Worcester murals to be finished this year. This is the third year in a row that Pow! Wow! Worcester has added murals to the city’s streetscape and schools.

Ms. Walsh said she has plans to make 3-D glasses available for the public at Worcester Wares.