Most listings are in the $30's per square foot per year. The Center City region is seeing a decrease in rates. In the last 3 months, the median rate fell $2 per sqft per year. That's a 7% decrease in rent.
Compared to the rest of the Philadelphia market, the Center City region has less expensive rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 219 listings have been made available, so you'll want to check back regularly for new listings. About 4% of the available space in the Center City are subleases, so you will probably need to consider the implications of signing a direct lease with the building. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
Even though the median size is 5,300 sqft, there are still 0 new listings below 2,000 sqft. Most buildings in this market are approximately 20 stories. Most buildings in this area were built in 1930 and are Class A.