Today, the church has three naves but originally it had two. It was not until the 1400s that south nave was built.
The floor of the church was originally paved with cobble stones but today is made up of grave slabs from different epochs.
The first king to be buried here was Magnus Ladulås (died 1290). He rests in the chancel in front of the alter to the left and at his right side lies Karl Knutsson Bonde (died 1470).
The mausoleums were built in 1573 and 1574 by Johan III. The kings' original graves are situated under the mausoleums. If one stands facing the alter one can see the Gustavian chapel built 1629-1643.
In the lower crypt, which is not open to visitors, lies king Adolf Fredrik (died 1771), Gustaf III (died 1792), Gustav IV Adolf (died 1837) and Karl XIII (died 1818).
By the left and respectively right walls stand the sarcophaguses of Fredrik I (died 1751) and Ulrika Eleonora the Younger (died 1741).
In the Karolinska crypt, which is situated under the Karolinska chapel, rests Karl X Gustav (died 1660) and Hedvig Eleonora (died 1715), Karl XI (died 1697) and Ulrica Eleonora the Elder (died 1693) as well as five of their children who died in infancy.
In front of him lies Queen Desideria (died 1860) in a sarcophagus of green marble from Kolmården. By the walls stand brown limestone sarcophaguses for other Bernadotte dynasty regents.
The last monarch to be buried in the Riddarholm Church was Gustav V (died 1950).
As the custom of burying members of royalty at Haga continued a Christian tradition was adopted and a new royal tradition was cultivated.
The Haga Wall, as it is called, is situated close to the Bernadotte chapel. Crown Princess Margareta's shield on the Haga Wall is unique amongst the church's shields.
It is not a seraphim shield. Instead of the Order of the Seraphim's chain of angels and crosses around her coat of arms is a heraldic garland of marguerites.
It depicts the scene where Dante and Beatrice reach the ninth heaven, governed by the Seraphim, the holiest of all choirs of angels.
In Beatrice's beautiful eyes, Dante sees the reflection of light - a point of eternal light - the Holy Spirit.