El Born scarcely needs a guided tour but if you want to use it as the base for a wider exploration of old Barcelona then this tour would be great if you like bikes.
https://www.viator.com/tours/Barcelona/Barcelona-Half-Day-Bike-Tour/d562-3993FTBB
Try also a do it yourself walking tour based on the Frommers guide:
https://www.frommers.com/destinations/barcelona/0045020034.html
With it's historic and cultural traditions going back hundreds of years El Born, the Height of Barcelona, offers many sites of interest to the culture lover.
Of course merely walking the streets rich in history such as the Passeig del Born is itself an amazing cultural experience. And the nightlife and bar scene is a form of modern culture. But for the more traditional experience don't miss the many small art galleries in the district.