Location? Actually, it isn't everything

John McGrail moved to Boston from his family farm in Ireland in 1987, and said he'd told himself he'd only stay six months.

But four years later, he'd saved enough money for the down payment on a three-family house Dorchester and fixed it up. The investment was one he'd not only made in the community, but in his future.

Today, McGrail heads the Boston-based Mayo Group, a real estate firm that owns 1.5 million feet of commercial space and 2,000 residential units.

''I always had big aspirations," said McGrail, 38, who is originally from County Mayo. ''I started out sweeping floors -- and I can walk into a building and come out the other side and know within 5 percent what it will cost to remodel it."

McGrail built the business making risky investments in Roxbury, Dorchester, and downtown Lynn, converting run-down buildings into condos.

He's taken on other unlikely deals such as turning defunct nursing homes into apartments in Mattapan. Now the Mayo Group has 115 employees and owns property throughout New England. The group has holdings in the housing market in Austin, Texas, and may expand to Atlanta.

''We've been entrepreneurial -- we had the courage to go into neighborhoods no one would touch," said McGrail. McGrail said he's often asked why he decided to invest in Boston's toughest neighborhoods well before the real estate market boom made every investment seem a good bet. ''And the honest answer is, it was all I could afford," he said.

McGrail hasn't limited himself to quiet deals, though. Earlier this year, he bought waterfront property in Boston, spending more than $17 million at 51 Sleeper St. in the Fort Point Channel area. He signed on the United Way as a long-term tenant.

The Mayo Group just received City Hall approval for turning the defunct Eblana brewery in Mission Hill into loft-style condos. The brewery was built in the 1880s and will become 83 condos, with 11 designated as affordable units. ''We see it as a diamond in the rough," McGrail said.

McGrail describes the residential side of the Mayo Group's business as building ''good, safe housing for working-class people."

But buying up blighted buildings and cleaning them up is not without controversy, since rents go up for some tenants at the improved rental properties.

Last July, a group of tenants from Hyde Park and Mattapan protested rent increases in at several properties, arguing the rehab was not worth the higher rates. He's been criticized by some tenant's-rights groups after saying he preferred to negotiate with tenants on a case by case basis, rather than collectively.

McGrail said he's in negotiations with tenants'-rights groups, but nothing has been resolved.

He says the reality is that the cost of cleaning up old buildings raises rents in places where rents might have been 40-50 percent less than market rates, due to their run-down condition.

''You are never going to be able to make everyone happy," he said. ''You look at all the housing we've created and it's a small minority of people who don't agree with the work we've done."

He says he hasn't regretted his decision to stay in Boston.

''It's a tough city, and it's tough because it's a great city. and if it wasn't a tough city, it wouldn't be a great city," McGrail said.