Hear several hours of Baroque music on one of the Lehigh Valley’s most magnificent organs when the Lehigh Valley Chapter of the American Guild of Organists holds its annual “Bach Marathon,” 3 - 7 p.m. March 24, St. John’s Evangelical Lutheran Church, 37 S. Fifth St., Allentown.

Members and friends of the Guild perform music by Bach and composers who influenced or were influenced by Bach in 30-minute time slots.

The church’s organ is featured in several organ concerts as part of the “Arts at St. John’s” series, approaching its 30th anniversary and celebrating music as God’s creation.

“The organ is our real claim to fame here,” says Eric Gombert, cantor at St. John’s. “It’s among the largest and most significant pipe organs in the region.”

The church recently celebrated the 25th anniversary of the renovation of the Skinner organ, which has four manuals and 87 ranks.

In the next “Arts at St. John’s” concert, Gombert, organ, accompanies the Muhlenberg College Women’s Ensemble and Chamber Choir, concert, 3 p.m. March 31.

The two ensembles, under the direction of Christopher Jackson, will perform “Missa Brevis” by Britten, The Opus 39 Motets by Mendelssohn and “Chichester Psalms” by Bernstein. The program includes “Lobet den Herrn” by J.S. Bach, “The Snow” by Elgar, “Hor ch’el ciel e la terra” by Monteverdi and “Five Hebrew Songs” by Whitacre.

The organ will be featured in “Bach at Noon” presented by the Bach Choir of Bethlehem, noon June 11, July 9 and Aug. 13 in the church, in collaboration with “Arts at St. John’s.”

Upcoming “Arts at St. John’s” concerts include:

Three concerts in collaboration with the Allentown Symphony Orchestra: Allison Kiger, flute and Oren Fader, guitar, 3 p.m. April 3; Omri Barak, trumpet, 12:10 p.m. April 23, and Elysium String Quartet, 7:30 p.m. May 31

Sean Burns, organ, 3 p.m. June 3

Allentown Band; Eric Gombert, organ, 3 p.m. Sept. 29

Harmonic Brass of Munich; Eric Gombert, organ, 3 p.m. Oct. 12

“Mozart Requiem,” in memory of Joseph Sekulski, 3 p.m. Nov. 3.

The St. John’s church organ was built by Ernest M. Skinner and Son of Massachusetts in 1938 and had 52 ranks (3,359 pipes) that featured orchestral and color reeds stops, large-scale diapasons, strings, two Vox Humanas and large flutes.

In 1969, Lehigh Organ Company, Macungie, renovated and expanded the instrument, adding a festival trumpet to the ceiling of the church’s nave.

In 1992, the Reuter Pipe Organ Company was hired to rebuild, redesign and refurbish the organ, using many of the old ranks of pipes. The company built new ranks and added a new four-manual console with solid-state switching and memory capabilities.

In 1998, five digital stops were added by the Walker Technical Company, Zionsville, bringing the number of ranks to 87.

“Arts at St. John’s” concerts are free, with donations accepted.

Parking is available at meters along streets in the vicinity of the church and at the Community Parking Deck, Sixth and Walnut streets, Allentown, one block west of the church.

Information: stjohnsallentown.org/arts.html.