The Wrigley Building, one of Chicago’s iconic structures, dates back to the early 1920s, when William Wrigley Jr. settled on a site along Michigan Avenue, hard by the Chicago River, for the headquarters of his chewing-gum empire.

It has loomed over the city’s skyline ever since, though it underwent a makeover after being purchased in 2011 by investor Byron Trott and the co-founders of Groupon Inc. The building’s infrastructure, public areas and office suites were upgraded. The plaza between its two towers was transformed into a vibrant dining and shopping space. Such retailers as Walgreen’s and Ghirardelli opened outlets within the building.

The goal was twofold — preserve the building’s personality while making it attractive to businesses — which in turn offers an object lesson for others in the real estate world looking to walk that fine line between maintaining a property’s heritage while rehabilitating the place.

When undertaking such a project, it is wise to consider the Secretary of the Interior’s standards for the rehabilitation of a historic building. Those guidelines call for “minimal change” and require that “the historic character of a property shall be retained and preserved.” Also, additions or exterior alterations are not to alter the place’s historical integrity.

It is also a good idea when in the planning stages to reach an understanding of what makes a place unique, historically and architecturally. If something particularly notable took place there, it is worth considering whether the property should be restored to the time period in question.

Beyond that, consider what you need from the place, then strive to make it useful and functional, while at the same time preserving its key historical and architectural features. A historical home, for example, would preserve the look and feel of a bygone era, while featuring modern electrical, mechanical and plumbing systems.

The website also raised several points about rehabilitating a property, urging that changes be “non-intrusive and compatible with the house’s design and style” and true to the property’s historic and architectural roots. Additions, however, should be distinctive, so that the place’s history is “visible and transparent.”

There are numerous examples of rehabilitated historical buildings, with “compatible but differentiated designs” and additions that fit the decor. Storefronts offer their own special challenges, not the least of which is whether the original appearance of the place can be maintained while the interior is altered.

An example of what can be done when it comes to homes comes courtesy of  a remodeler based in Lawrence, KS, named Natural Breeze. That company took a house dating back to 1911 and made sure to rebuild the porch in such a way that it was faithful to the structure, not to mention the historic district of which the home was a part. The renovation of the four apartments was extensive, but the goal of preserving the place’s personality was achieved.

There is obviously no one-size-fits-all approach to the rehabilitation of historic properties, but these guidelines — as well as an understanding of your needs and capabilities — should allow you to reach common-sense conclusions about the job at hand.