That structure is an entry monument welcoming everyone to the City of St. Petersburg. The monument is similar to the downtown St. Petersburg entry monuments located on the eastern terminuses of both downtown feeders, Interstate 375 and 175.
The entry monument was proposed for the location north of the 4 St N exit for many years from what I understand. Unfortunately, there were no monies in the budget for the City of St. Petersburg to erect this important entry monument; however, a prominent St. Petersburg businessman, Bill Edwards (whose company, Big 3 Entertainment, operates the City owned Mahaffey Theater), stepped up to the plate and donated money for the entry monument’s construction.
Here’s a picture of what it looks like:
The new entry monument on southbound Interstate 275 just before 4 St N (Exit 32) does indeed put the City of St. Petersburg’s best foot forward in welcoming our visitors to our city. After all, first impressions last a lifetime!