Most of us in South Orange County know the names
Marguerite. Alicia. Avery. Jerónimo.

They’re streets we drive every day.

But those names aren’t random. They trace back to one family that shaped this entire region: the O’Neills. Yes, as in O’Neill Regional Park.

In the late 1800s, Irish immigrant Richard O’Neill helped build a cattle empire across thousands of acres of what is now Mission Viejo, Rancho Santa Margarita, Ladera Ranch, and San Juan Capistrano.

Long before master-planned communities, this was working ranch land. Cattle, droughts, handshake deals, and grit.

The street names were personal.

👩‍🌾 Marguerite was Richard O’Neill’s wife.

👰 Alicia (Alice) was his daughter-in-law.

👦👦 Jerónimo (Jerome) and Antonio were Alicia’s sons.

💍 Avery came later, connected to Alicia’s second husband and the next chapter of the family’s legacy.

🏅 Before the 1984 Los Angeles Olympics, today’s Olympiad Road in Mission Viejo was originally named O’Neill Parkway — it was renamed in honor of the Summer Games when Mission Viejo hosted Olympic cycling events.

You can step straight into that history at the O’Neill Museum, located in the Los Rios Historic District in San Juan Capistrano.

Built between 1870 and 1880, the approximately 150-year-old home now serves as the headquarters of the San Juan Capistrano Historical Society. Inside, the museum displays family photographs, ranch artifacts, and documents that trace how vast cattle holdings eventually evolved into modern South Orange County communities.

On the grounds, you can also explore:

1. The Silvas Adobe, restored to reflect its original two-room 1794 footprint.

2. The historic Old Jail, built in 1896 and once described as looking like a giant bird cage.

3. The Oyharsabal House, a late-1800s board-and-batten structure that was saved from demolition.

4 The Arley Leck House, a 1918 bungalow moved to the property and now used to display historical collections. It’s usually not open to walk through, but can be rented for events.

A Real Ghost Story

Local lore says former owner Albert Pryor still lingers. After his death, tenants reportedly claimed to see a man sitting on the porch smoking a cigar, and some said they could smell tobacco drifting through the house. Whether you believe it or not, the story has become part of the museum’s reputation over the years.

The O’Neill story did not end with cattle.

Through marriage, the family became connected to the Moiso name. Anthony R. “Tony” Moiso is the Chairman and CEO of the Rancho Mission Viejo Company, which continues to manage ranching, farming, conservation land, and development across tens of thousands of acres in South Orange County.

Tony traces his lineage directly to the O’Neill family through his mother, Alice O’Neill, who was the daughter of Marguerite O’Neill.

His father (Alice’s first husband) came from the Moiso ranching family. That union tied together two long-standing California ranch legacies, and Tony would go on to lead the business operations of the remaining ranch lands.

Today, Rancho Mission Viejo still operates active cattle and farming operations while overseeing development and conservation across the historic ranch property.

🏛 O’Neill Museum – Step into O’Neill family history inside this 19th-century home run by the San Juan Capistrano Historical Society. The museum is typically open Tuesday - Saturday 9-12 / 1-4

🚶‍♂️ Los Rios Historic District – Walk the street that’s widely regarded as the oldest continually inhabited neighborhood in California, with original adobes dating to the late 1700s.

🗺 Weekly Historic Walking Tours – The San Juan Capistrano Historical Society offers free guided tours starting at the train depot every Saturday at 1 PM, walking through Los Rios and its stories.