National Register of Historic Places in Sonoma County, California
Sonoma Pueblo was the chief military base of the Mexican Government in Alta California.
In 1823, Misión San Francisco Solano de Sonoma was founded. It was the the last (northernmost) of the twenty-one Alta California missions and the only one established under Mexico rule.
In 1835, General Mariano Vallejo laid out the plaza as a parade ground for Mexican soldiers stationed at Sonoma Presidio. It is the largest central plaza in California.
On June 14, 1846, the raising of the Bear Flag in the Plaza marked the beginning of the American revolt against Mexican rule.
Source: NRHP nomination form submitted in 1975.

Sonoma Plaza has been a National Historic Landmark (NHL) since 1960 when the National Historic Landmark program was established. 92 properties were immediately designated as National Historic Landmarks including seven in California. Sonoma Plaza was the northernmost California landmark.
The district was listed on the National Register of Historic Places in 1975. The NRHP district is slightly larger than the NHL district.
All seven California landmarks were built during the rule of Spain or Mexico:
When the National Register of Historic Places was established in 1966, the National Historic Landmark program was encompassed within it.

The boundaries of the NRHP district were expanded in 1992 to include properties on Broadway and the north side of East Napa Street.
| Name | Year | Address | Remarks | Sort Address | Sort Name |
|---|---|---|---|---|---|
| Duhring Building | 1892 | 498 1st Street East | Street 01 E 0498 | Duhring Building | |
| Baptist Church | 1850 | 542 1st Street East | Street 01 E 0542 | Baptist Church | |
| Poppe House | 1847 | 564 1st Street East | Street 01 E 0564 | Poppe House | |
| Nash - Patton Adobe | 1847 | 579 1st Street East | Street 01 E 0579 | Nash - Patton Adobe | |
| El Dorado Hotel | 1840 | 411-17 1st Street West | Street 01 W 0411 | El Dorado Hotel | |
| Salvador Vallejo Adobe | 1843 | 421 1st Street West | Street 01 W 0421 | Salvador Vallejo Adobe | |
| Ruggles Building | 1870 | 433 1st Street West | Street 01 W 0433 | Ruggles Building | |
| Sonoma Antique Shop | 1850 | 447 1st Street West | Street 01 W 0447 | Sonoma Antique Shop | |
| Batto Building | 1909 | 453 1st Street West | Street 01 W 0453 | Batto Building | |
| Masonic Hall | 1909 | 465 1st Street West | Street 01 W 0465 | Masonic Hall | |
| Leese-Fitch Adobe | 1841 | 487 1st Street West | Street 01 W 0487 | Leese-Fitch Adobe | |
| Vasquez House | 1851 | 541 1st Street West | Street 01 W 0541 | Vasquez House | |
| Clewe Residence | 1880 | 531 2nd Street East | Street 02 E 0561 | Clewe Residence | |
| Duhring Residence | 1860 | 532 2nd Street East | Street 02 E 0562 | Duhring Residence | |
| Sonoma City Hall | 1906 | Plaza | Plaza 01 | Sonoma City Hall | |
| Bear Flat Flag Staff and Monument | 1913 | Plaza | Plaza 05 | Bear Flat Flag Staff and Monument | |
| Mission San Francisco Solano de Sonoma | 1823 | East Spain Street and 1st Street East | Spain E 0000 | Mission San Francisco Solano de Sonoma | |
| Taylor House | 1852 | 114 East Spain Street | Spain E 0114 | Taylor House | |
| Blue Wing Inn | 1849 | 133 East Spain Street | Spain E 0133 | Blue Wing Inn | |
| Ray-Adler Adobe | 1848 | 205 East Spain Street | Spain E 0205 | Ray-Adler Adobe | |
| Castagnasso House | 1850 | 256 East Spain Street | Spain E 0256 | Castagnasso House | |
| Casa Grande Site and Servants Quarters | 1840 | West Spain Street | Spain W | Casa Grande Site and Servants Quarters | |
| Sonoma Barracks | 1836 | West Spain Street and 1st Street East | Spain W 0030 | Sonoma Barracks | |
| Swiss Hotel | 1843 | 18 West Spain Street | Spain W 0018 | Swiss Hotel | |
| Toscano Hotel | 1857 | 20 West Spain Street | Spain W 0020 | Toscano Hotel | |
| Country Inn | 1896 | 110 West Spain Street | Spain W 0110 | Country Inn | |
| Jones Adobe | 1842 | 143 West Spain Street | Spain W 0143 | Jones Adobe |
This wood-frame structure has a Classic Revival design characteristic of the early 1850s. When it was listed on the National Register, it housed an antique shop.