The Irish immigrants who had arrived in Dover to work in the mills desired their own Catholic Church, so Father Charles Ffrench purchased land at the corner of Third and Chestnut. A wooden, gothic church was built in 1830 and the parish was named St. Aloysius. A two wing addition was put on in 1839 as the parish expanded. In 1870, the old church was moved back on the lot and a new brick building started in front. A fire on Halloween burned the old church and a lot of the new structure. Eventually construction resumed and the present brick building started in front. The brick church was completed in 1872 and renamed St. Mary’s. The rectory at the rear was built in 1875 and later remodeled. In 1947, the Diamond Jubilee Anniversary of the parish, the heavy cornice and crosses on the tower were removed and replaced with a new roof and a single cross. St. Mary’s celebrated its 150th anniversary in 1980.
From the 1984 Heritage Walking tour booklet
When ground was broken at the corner of Chestnut and Third streets in 1828, to build St. Aloysius Catholic Church, there were so many “foreigners” in the Third and Fifth Street area that it was locally called “Dublin.” Dover’s population had increased so with the coming of the mills, that the town was second in the state in size and wealth. The church was dedicated in 1830 and was built on land purchased by Father Charles Ffrench.
Before they had a church, in 1826, the Roman Catholics had been meeting in private homes, John Burn’s house on Chapel street for one, and in the old Court house on Tuttle square. Forty years after St. Aloysius was built, it was destroyed by fire.
There was some talk of locating a new church on Central Avenue where St. Mary’s Academy now stands, but the head of the board died before the plans were completed. So St. Mary’s, the present church, was built on the St. Aloysius lot. It was dedicated in 1872.
From “City of Dover, New Hampshire Centennial Celebration 1855-1955” compiled by the Historical Program Committee, 1955.