The  Maesgeirchen Estate was built on the outskirts of the City of Bangor, not far from the A5, the main trunk road which runs between Holyhead and London. The name Maesgeirchen describes the oat field that was a part of Tyddyn Llwydyn Farm, which was situated exactly where the council estate is situated today.

There were so many slum dwellings, at the centre of Bangor City, after the First World War, that it was essential for Bangor Council  to do something about this situation.  Under the 1930 Housing Act an allocation of funding was offered to the Councils  by the Labour Government  to build council houses.

The owners of the land  on the outskirts of the city were not willing to sell land to the Council, for the purposes of building council houses, but Lord Penrhyn offered to sell 70 acres of land  to the Council., that was a part of the Maesgeirchen Farm, which was situated on the southern slopes of Bangor Mountain and overlooking the Cegin Valley

The Housing Commitee's commendation of the Maesgeirchen site was greeted with a storm of protest as the land was situated on the other side of Bangor Mountain, and far away from the center of the city. To rehouse people there would be like turning them out of the city.  But on 15 June, 1936 a resolution to build houses  on the Maesgeirchen site was carried by the Housing Committee with a majority of one vote.  The work of building the Maesgeirchen Estate proceeded immediately and 304 houses, on Penrhyn Avenue, were built by 1939.    A piece of land, at the centre of the estate, was allocated for the future development of  shops and a Community Centre.  In 1952 a Chapel was built by the Presbyterian Church of Wales but, unfortunately, the chapel has by now closed its doors but the building is being used as a Youth Centre.  In 1958 a church Eglwys y Groes was built there by the Church of Wales.  238 houses were built there between 1953-58 and 102 houses were completed in 1967-68, which were called Tan-y-Bryn, as well as Gancegin School.  By 1968 there was 3,000 people living on the estate.  Between 1983 and 1998 houses called Tan y Coed were built and these houses border the school's perimeter.  From the onset two shops have been a part of the estate and these two shops still  exist today, having been modernised, together with a chip shop, newspaper shop, hairdresser's shop and a post office.

When building started on the Maesgeirchen Estate the council departed from its custom of giving Welsh names to all the streets and the road joining the estate to the A5 was called Penrhyn Avenue, in honour of Lord Penrhyn who had provided the site.  Other names given to the streets were Greenwood Avenue, commemorating Arthur Greenwood who  was the Minister of Health in the 1929-31 Labour Government,  and the architect of the Act under which the estate was built.  Kingsley Avenue honours Kingsley Wood, who was Minister of Health at the time the houses were built.  The estate was officially opened, by Lord Penrhyn, in November 1937 and, by building this estate, a discrete working class suburb, detached from the rest of the City of Bangor,  was created.