Typically, Class Bs are seen as older and middle-tier buildings. They aren't as flashy and amenitized as newer trophies and Class As, but they serve a purpose and aren't as out of date as Class Cs.

THE NEW YORK FACTOR

So why is there now an appeal for middle-tier buildings? Many office properties, especially Class Bs, were struggling not too long ago. However, New York City's resilient recovery since then has helped revive the property type, according to Levy. This is especially prominent in Manhattan, as that's where everybody in the city wants to be.

"[Tenants] are coming from Queens looking at this as an opportunity to move their business into the heart of the world, and move it from Queens to Manhattan, where the labor pool is the best, [and] the community transportation is the best," said Levy.

While leasing in Manhattan cooled month-over-month in February, deals are up 38.3 percent year-over-year and 18.6 percent from the 10-month average, according to a report from Colliers.

MIDTOWN SOUTH STANDING OUT FOR CLASS B'S

Levy listed one submarket that's getting attention for Class B properties in particular -- Midtown South. He said that the "garment district area is burgeoning because that's where [the tenants] want to be, and now they're coming back to the office."

Meanwhile, one area tenants appear to be avoiding is SoHo due to the limited office supply. That's, of course, giving businesses fewer options to choose from in the neighborhood.

Another element that stands out about Class B's in general is the "cool hipper" vibe they offer, according to Levy. Additionally, it's worth noting that rents aren't as high as the upper-scale properties. That's something that could again entice a tenant to move into Manhattan instead of staying at another borough in NYC.

STRATEGY BEHIND MIDDLE TIER BUILDINGS

When making acquisitions, an investment firm may have a different strategy. For example, many might look to transform a Class B into a multifamily asset or upgrade it in hopes of flipping it and making a premium off it at a later time.

For Adams, if purchasing, the end goal is to keep a Class B office long-term and lease it out. But renovations aren't out of the question either.

"If we were to buy a building, it would be at a price that we think makes sense, [and] turn it into our standard type of building," Levy explained while adding that might include "new elevators, new windows," and transform it in "pristine condition and make it the best B Building it can be."

Some of Adams' mid-tier offices offer upscale perks like conference centers and even fitness classes.

But the best amenity of them all? That's performing as a quality landlord, which relates to the relationship of tenants and understanding their situations while adjusting to them, as noted by Levy.

The performance of Class B's and how they evolve, will be a question in the future. While a recent report from Avison Young revealed that Class A and trophy properties are now the predominate asset type in Manhattan, Adams is proving that Class B's can still work in the city.