The ROM Crystal, which opened in 2007, is getting critical pans from architecture buffs. (Jeff Speed/Royal Ontario Museum)

The Royal Ontario Museum's Michael Lee-Chin Crystal addition took a critical drubbing from the Washington Post on Sunday, after writer Philip Kennicott voted it worst of the decade's architecture.

It's the second time in the past month the addition, part of the ROM's $270-million expansion opened in 2007, has been panned.

Earlier in December, travel site VirtualTourist.com put the Crystal, named after a philanthropist who gave generously to the project, in eighth place on its list of the world's top 10 ugly buildings.

The Post's Kennicott said he found the glass and aluminum addition to be dramatic from the sidewalk, where it hangs over Toronto's Bloor Street.

"His aluminum-and-glass-clad crystalline forms grow out of the building's original 1914 structure, and from the street it's dramatic," Kennicott writes. "But go inside and you need a map to move around its irrational and baffling dead spaces.

"Sure, there were a lot of Wal-Marts thrown up in the Aughts, but Daniel Libeskind's addition to the Royal Ontario Museum in Toronto surpasses the ugliness of bland functional buildings by being both ugly and useless," he added.

Celebrity architect Libeskind famously created the initial design on the back of a napkin and the construction was delayed by cost overruns and technical difficulties.

Critics were divided on their opinions when the building opened, with many praising the bold design as a fresh addition to Toronto's usual stodgy architecture.