The Secret Life of Buildings: Bay Windows

There is something irresistible about a bay window. Whether it’s the abundant light it brings into the home or the constantly changing views it affords from inside. As part of our “The Secret Life of Buildings” series, we’ve decided to explore the history of this unique architectural feature that adds value to buildings throughout the City, whether they were built two hundred years ago or yesterday.


The popularity of bay windows in Philadelphia can be traced back to England. Way back! Starting in the 5th century. During the Gothic period, 12th to 16th century, bay windows were known as “oriel” windows. 

An ornamental addition to the building, bay windows were added to cathedrals across Europe. A famous example is St. Sebaldus Church in Nuremberg built in 1361.  In private homes, the area inside the bay window alcove was often used as a house chapel. Meanwhile, in Islamic architecture, bay or oriel windows were used throughout the Arab world as a mashrabiva, a balcony from which women could view public life from behind a screen. 

St. Sebaldus Church

During the English Renaissance, 15th – 17th century, many of the grand houses of the Baroque period featured bay windows that illuminated the ornate detailing of the time. A variation of the bay window is the curved bow or circle bay window. These first appeared in 16th century England and migrated to the United States during the Federal period. 

One of the most exciting and innovative uses of bay windows was Oriel Chambers, built in Liverpool in 1864. It was the world’s first building featuring a metal-framed glass curtain wall, considered to be one of the most influential buildings of its age.

Oriel Chambers, built in Liverpool in 1864.

The Philadelphia Story

Although bay windows made their way across the Atlantic Ocean as early as the Federal Period, it was during the Victorian and Edwardian eras that they really exploded. An example is the bay window at 1219 Spruce, a Romanesque Revival townhouse designed by Philadelphia architect Frank Miles Day in the 1890s. The front of the house features a large bay window capped with a copper cornice with a corbelled design and two small shields. There is another bay window on the Camac Street side of the house. Day also used bay windows to bring light into Houston Hall when he designed it in 1896.

1219 Spruce Street – a Romanesque Revival townhouse designed by Philadelphia architect Frank Miles Day in the 1890s. Photo courtesy of Howard Silverman.

Around the same time, bay windows were making their debut on townhouses ringing Rittenhouse Square. From inside their grand mansions, the City’s elite, including Philadelphia Railroad president Alexander Cassatt and department store founder John Wanamaker, could gaze down upon the lively Square. 

Several opulent mansions with bay windows still exist on the Square, including 1912 Rittenhouse Street and 1923 Walnut. Bay windows are also a prominent feature of 1830 Rittenhouse Square, the first high-rise residential building on the Square, designed in 1913 in the Baroque style by Frederick Webber. 

When affluent people moved from Center City to North Philadelphia in the early 20th century, they were attracted to Gothic and Victorian mansions along North Broad Street and in Strawberry Mansion which featured not only bay windows, but circular windows built into turrets. 

A home in West Philadelphia with circular windows built into turrets

Architectural movements, such as Arts and Crafts and Art Nouveau, came and went, but the bay window remained a Philly staple. And not just for the affluent. They were used by builders of middle and working-class row homes in every section of the City throughout the 20th century. By adding three large windows angled out beyond the exterior wall, formerly dark, stuffy homes were filled with light and air.  

Various styles of bay windows in West Philadelphia
Various styles of bay windows

Contemporary Bay Windows

In the 21st century, bay windows have seen a resurgence. Their classic design is popular with homeowners seeking to maximize the natural light and optimize the space in their home while increasing its value.

Modern bay windows are either polygonal or square. The box bay window, which is shaped like a rectangular or square box, is still popular throughout Europe. Today, the term bay window is used to describe any window construction that extends from a building’s exterior wall. Interestingly, the box bay window is the hallmark of new apartment house construction in Philadelphia. 

Modern Bay Windows

When modern versions started appearing in Point Breeze, some older residents were so concerned by this sign of gentrification that they worked with a City Councilman to propose a ban on bay windows in their neighborhood.  However, Philadelphia Preservation Alliance cited bay windows as a defining characteristic of row homes in the Point Breeze section in the late 19th century, early 20th century two-story, single-family row homes. As a result, the ban wasn’t enacted.

Other examples of box bay windows can be seen in a four-story apartment complex on Front Street between Sansom and Walnut, affording breathtaking waterfront views.

Modern Box Bay Windows on Front St.

Bottom line? Bay windows add beauty and value to homes. They improve curb appeal, add natural light, and maximize available space. 

This article is part of a series titled “The Secret Life of Buildings” where we write about the history and architecture behind Philadelphia’s buildings. We’ve covered row house stylescommon Philadelphia brick stylestrinity homes, star bolts, and residential courts, among other topics. What else would you like to learn about? Follow us and DM us on Facebook or Instagram to let us know!