The site of the two-story retail and office building at 21st and Chestnut Streets in west Center City, now home to tenants including Monde Market and the Day By Day brunch spot, is being marketed for sale and potential redevelopment as a new high-rise.

At least $20 million is being sought for the 19,125-square-foot structure on a half-acre site, which was built in 1929 as a parking garage, James Galbally, who is marketing the property as a broker with commercial real-estate firm JLL, said in an email late last week.

The property at 2100 Chestnut St. is being sold by a unit of Philadelphia building owner Wil Rappaport's Sansom Asset Management, according to records filed with the city. It was previously owned by a partnership involving real estate investor Sam Rappaport, Wil's deceased father, and late businessman Lewis Katz, records show.

A marketing brochure prepared by JLL proposes potential uses for the site that range from renovating the building for a single user to clearing the parcel for a large project that takes advantage of the area's permissive zoning.

"Given the size of the lot and prime location on the corner of 21st and Chestnut Streets, the property could also be razed and redeveloped to capitalize on growing real estate trends in the market, such as a new luxury residential tower," the brochure's authors wrote.