This large, but not completely finished, 15th century church is an example of Brabantion gothic. Until 1868 it was the sole parish church in Aalst.
In former days there stood a much older church on the premises. After a fire in 1360 and demolitions by the people of Ghent, this old church was repaired with gothic elements.
Because the chapter church became to small for the growing population, and as a consequence of the good economic situation under the dukes of Burgondy, the rebuilding was initiated around 1480 under the laerdership of Jan Van Wouwe and continued by Herman de Waghemakere .
First the radial chapels with an ambulatory were added round the choir of the existing church. Then the old choir was replaced. This was probably finished round 1495. There are still some vaultal paintings from this period to be found.
During the second building period, between 1527 and 1554,the two-naved south transept was erected under the leadership of Laurens II Keldermans in Balegemstone. In 1551 2 crossbeams were added on the south side of the nave and around 1552 the building of the north porch was started. The religious troubles after 1565 brought about many destructions, among other things the gothic sacrament towers. The works were stopped many times due to continuous sieges and changes of power between 1576 and 1583. Urgent repairs could start steadily from 1595 on.
The third building phase started from 1650 on, when Gillis Nechelput and Geraard Spillebaut broke up the weather-beaten parts, and repaired the nave with crossing and stellar vaulting and the northern arch. From 1660 on the high vaults were added under the existing roofing, under the leaderschip of Jan Van der Moeren. The nave was shut with with a temporary stone wall. The construction of a huge west tower was planned but never realised.
In 1730 a Louis XV-western porch was added. The building hasn't changed afterwards, exept for several improvements and the building of a storeroom in 1911.
Between 1854 and 1867 thorough neo-gothic renovations took place under the influence of the architects Julius Goethals and Jean de Béthune. Among other things a gutter with gothic design was added. In the interior the same designs were added in the breastwork for the triforium. The replacement of the round north and south side towers by pinnacles made the building look even more gothic.
A fire 29 march 1947 destroyed the crossing tower and the roof of the nave and side naves. Two vaults of the south transnave collapsed and inside there was a lot of damage.
At that moment again repairworks were necessary: especially the crumbling ornaments and the replacement of the weak structure and roof.
One of the most mentionnable objects must shurely be the copper meridian line. It runs through the south transnave and vaulting. It was applied in 1839 by J.J. Leveau on advise of priest Johannes Thyssen s.j.. When the rays of the sun fall perpenducularly through the hole of the second lower window panel, it is midday according to the sun. If you keep in mind the added summer time, it is then officially about 14 h 16' 6'.
The oak portico of the St. Rochusaltar contains a painting of Pieter Paul Rubens where Sint Rochus is depicted as patron of the pest sufferers. This work was painted round 1624 in assignment of the guild of the hop and seed merchants. Underneath there are two scenes of the life of Saint Rochus and above the top is crowned with a painting of the Holy Mary with Jezus.