The business of making money world's biggest piggy bank

When it comes to making money, Wharton might be merely second-best in this city.

The United States Mint in Philadelphia is the largest mint in the world, as well as the oldest mint in the country. It is responsible for producing the portion of the 11 to 20 billion coins the system creates annually that are distributed east of the Mississippi River.

The mint differs from the country's three other mints (in Denver, San Francisco and West Point, N.Y.) in that it creates national medals to be awarded by Congress and keeps an artist on the premises.

On April 6, the mint reopened to the public for the first time since the Sept. 11 attacks. This is a good time to take a tour, as the visitor volume has not yet returned to the 400,000 people annually that the mint attracted in the past.

Spokesman Tim Grant said that the mint has "a great history" and is "always trying to improve" the experience for visitors.

Grant cited audio-visual enhancements and a new exhibit for the visually impaired that lets visitors touch the different kinds of coins produced at the mint as examples of additions that were put in place during the tour's hiatus.

"It's completely renovated. We did a lot of upgrades after 9/11," Grant said. "We are looking to put a few more hands-on" exhibits in place.

The tour details the process of minting money, from the creation of the giant clay models that artists use to perfect their designs to the dies -- negative images made of steel -- that machines use to imprint coins.

Between the exhibits are views of the floor of the mint, where four-ton coils of metal are transformed into "blanks" that presses strike into shiny new coins at a rate of 13 coins per second.

The mint prides itself on housing a variety of artifacts from its long and distinguished history, such as a gold medal presented to Revolutionary War hero Gen. Anthony Wayne and a coin press from the tenure of original mint director, astronomer and Penn professor David Rittenhouse.

The original press provides a stark contrast to the powerful machines on the floor, demonstrating that at the time of the mint's founding in 1792, coins were practically made by hand.

All tours of the mint are self-guided. The mint is open for visitors between 9 a.m. and 3 p.m. Monday through Friday, excluding federal holidays.

The mint is located off Independence Mall on Fifth Street between Arch and Race streets.

Coins aside from pennies minted in Philadelphia can be distinguished by a 'P' on the heads side.

Making the moolah - Location: Near Independence Mall on Fifth Street between Arch and Race streets - Tour Hours: 9 a.m. to 3 p.m. Monday through Friday - Reopened to the public: April 6 after closing for over three years after the Sept. 11 attacks

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