For the most part that means portraits of somber-looking men, but the latest addition is different a huge, vividly colored light sculpture commemorating the decades-long battle that won British women the vote.
The first abstract artwork created for permanent display in the 19th-century parliamentary complex, "New Dawn " was unveiled today on the 150th anniversary of the first mass petition to Parliament calling for women to have the right to vote.
It would be more than 60 years before the goal was achieved, and artist Mary Branson wants her work to pay tribute to the thousands of people who fought for women's voting rights over the decades.
But Branson, who spent six months exploring Parliament's archives, said she was moved by "all the women that I'd never heard about, ordinary people like ourselves."
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"There were so many women coming in relentlessly day after day," she said. "Petitioning, protesting."
Branson calculated how many petitions calling for female suffrage were submitted to Parliament between 1866 and 1918, when women over 30 were granted the vote. (Full voting equality with men took another decade).
There were almost 16,500, featuring more than 3 million signatures.
Branson found visual inspiration in Parliament's Act Room, where thousands of laws stretching back centuries are stored on parchment scrolls.
"New Dawn" consists of 168 circles of hand-blown glass inspired by the scrolls, mounted in a 4 meter-by-6 meter (13 foot-by-20 foot) ellipse.
The sculpture is lit from behind in a rainbow of colors to reflect the many strands of the votes-for-women movement. The lighting changes over a 12-hour period timed to the tides of the River Thames that winds through London, symbolizing the unstoppable tide of change.
"It's a fitting tribute to the champions of liberty of the past, as well as an inspiration for future generations," Commons Speaker John Bercow said of the artwork.