Sergio Rok’s company is the largest property owner in downtown Miami, but he prefers to fly under the radar.

About the only place you might find him is walking around Flagler Street, which is also known as Natan R. Rok Boulevard, named after his dad, the founder of Rok Enterprises. Sergio Rok still conducts business in much the same way his dad did, dealing directly with each of his approximately 300 tenants.

The company owns 17 buildings downtown, plus another nine in other parts of Miami-Dade County. Some of these properties have been part of the portfolio for more than three decades.

Last year he sold three properties downtown -- only the second time the family has sold any of its downtown assets. Before that, Rok sold only one property five years ago. But Rok said he isn’t looking to cut back his presence downtown.

“Once you stabilize an asset, the upside is limited so you look for a good time to sell,” Rok said.

Rok, who doesn’t usually agree to media interviews, agreed to answer written questions for The Miami Herald.

Here’s what he had to say:

Q. At what point did your family / Rok Enterprises start buying property in downtown Miami and why?

My father opened his first retail men’s clothing store on Flagler Street in the 1960s. He felt comfortable there because downtown Miami’s business environment back then was similar to the one in Havana, Cuba, where he had had a business. He started buying properties in the Central Business District in 1978. We both shared the vision that downtown Miami would someday become an international city.

Q. How did you end up as the largest commercial landlord downtown?

Between 1978 and 1998 we assembled over 20 properties in the CBD. We never really thought about becoming a major commercial landlord. We believed in Miami’s future, so when we saw a good opportunity, we bought.

Q. Why did you decide to sell three properties downtown late last year? Is this part of any broader plan to liquidate assets?

With the retail condominium at 101 East Flagler Street, tenants (Subway and Radio Shack) had long-term leases and the capital gains taxes were increasing in 2013. Flagler Station was sold for primarily the following reason: Sabadell Bank’s lease (anchor tenant) was expiring December 2012 and replacing them would be very difficult. As to the remaining 17 properties I own in the Central Business District, I have no plans to sell any of them.

Q. What kind of investments are you making currently in renovating and upgrading your existing downtown properties?

We are evaluating all our properties. The footprint and location of each one determines what can and can’t be done. We are interested in bringing better retail and more residential.

Q. Where do you see the redevelopment of downtown Miami?

There is more residential than ever, so the population has increased, but national retailers are still holding back. The DDA is working on the Flagler Street Improvement Project, which is critical if we are to attract national chains.We need the city, county and private sector to work together to bring about change. This is a very complex area with a lot of individual owners, and few big parcels. I truly believe in the future of downtown but a lot more needs to be done. It requires planning and patience.

Q. What was your first job?