This Federal-style brick house above Main Street was built in 1828 by William Ellicott, a grandson of one of the founding brothers, and was the last residence built by the family that gave the town its name. It later passed to Judge John Snowden Tyson, whose descendants lived in it for the better part of a century.
The county now operates Mount Ida as a visitor centre and small museum about the Ellicotts and the early industrial history of the Patapsco valley. It's a sensible first stop if you want orientation before walking down into the historic district — and the lawns give one of the best views in town.