Dedicated to Saint Blaise, the church of Havelu is oriented and comprises a single nave. Its construction dates back to the 16th century.
The choir, older and narrower than the nave, ends in a three-sided chevet. Constructed of flint blocks, the building is erected on a sandstone base. Two-stepped buttresses rise to the cornice.
The western door appears to date from the 19th century, based on a Gothic-inspired model. It consists of a pointed arch with two tori exposed by wide grooves resting on prismatic bases. A lowered arch supports the blind tympanum. A shell is carved on the lintel of the south door, now walled up.
A pointed octagonal spire rises from the bell tower. The roof is slate. Inside, the roof structure is exposed and retains the original stencilled decoration on the shingles. The name of the clergyman who commissioned it can still be seen: "M[ai]stre Jehan Menere p[re]b[t]re chaplain of this place."
The furnishings of Havelu church are remarkable for their uniform 18th-century decoration. A partition altarpiece is located in the choir. Signed and dated by the artist, Pierre Pilastre (1753), it features, in the center, a painting of the Resurrection, inserted between two fluted pilasters flanked by scrolls with floral and fruit motifs and topped with fire pots. At the ends, each of the two doors is surmounted by a painting, one depicting Saint Blaise, the other Saint Barbara. At the choir entrance, the triumphal arch—by the same craftsman—also survives. A work bench, a confessional, and a lectern from the same period complete this decorative ensemble.
In 1998, the Sauvegarde de l'Art Français (French Art Protection Association) granted a donation of 60,000 francs to strengthen the bell tower's framework.