Center City's 500º will serve its last burger Saturday night, Dec. 5 after 5½ years.

Owner Rob Wasserman says he will convert the space at 1504 Sansom St. into a branch of Snap Custom Pizza, a growing chain of BYOB parlors serving create-your-own pizza and salad, plus desserts and soft drinks. (It's a control freak's dream: It is one price for a choice of dozens of toppings, and there is a gluten-free option.)

Wasserman, who also owns Rouge on Rittenhouse Square, is now a partner in Snap, which Pete Howey and Aaron Nocks (Peace a Pizza, New Hope Soda) founded last year across from the SEPTA station in Ardmore. It's also a block from Wasserman's fancier pizzeria, Parlor Suburban Square.

Snap opened its second location last week at Main Street at Exton.

The Sansom Street location is due in early February.

Snap, flush with investment backing and architectural work by Joshua Otto, plans to open 15 locations in the region within the next 18 months.

Also on the way is a Snap conversion of the longtime Rosemont Peace a Pizza location (Hope's Cookies will remain) and a location on the campus of the University of Delaware.