Ohio Company Land Office

{{Use mdy dates|date=March 2025}}

{{Infobox NRHP

| name = Ohio Company Land Office

| nrhp_type = cp

| nocat = yes

| partof = Marietta Historic District

| partof_refnum = 70000523

| designated_other1_name = Campus Martius State Memorial

| image = Ohio Company Land Office 2010 08 25.JPG

| caption =

| location = Washington and 2nd Sts., Campus Martius Museum, Marietta, Ohio

| coordinates = {{coord|39|25|16.75|N|81|27|41.5|W|display=inline,title}}

| locmapin = Ohio#USA

| built = 1788

| architect = Ohio Company of Associates

| architecture = Log office building

| added = November 10, 1970

| designated_nrhp_type = 1974

| area = less than one acre

| refnum = 70000523{{NRISref|2009a}}

}}

The Ohio Company Land Office is one of the original buildings of the city of Marietta, Ohio, United States. The Office is listed individually in the National Register of Historic Places and as a contributing property to the Marietta Historic District.

The Land Office was built after Ohio Company of Associates landed at Marietta in 1788. The Office was built at approximately {{Coord|39|25|16.75|N|81|27|47.25|W|type:landmark_region:US-OH_scale:1500|display=inline|name=Ohio Company Land Office - Original Location}}. In 1791 the building was moved away from the Muskingum River so it could be protected by the guns of Campus Martius.{{cite book |last= Knepper |first= George W. |title= The Official Ohio Lands Book |publisher= The Auditor of State |year= 2002 |url= http://www.auditor.state.oh.us/Publications/General/OhioLandsBook.pdf |page= 29 |url-status= bot: unknown |archiveurl= https://web.archive.org/web/20110716151950/http://www.auditor.state.oh.us/Publications/General/OhioLandsBook.pdf |archivedate= 2011-07-16 }} From this location, Ohio Company surveyors plotted the company's entire purchase in southeastern Ohio, more than {{convert|900000|acre}} in total, under the direction of Rufus Putnam as the company's chief.Owen, Lorrie K., ed. Dictionary of Ohio Historic Places. Vol. 2. St. Clair Shores: Somerset, 1999, 1397. Image:ohio company office 1903.png |url=https://archive.org/details/historymarietta00summgoog}}]] The building is a simple log structure with a gabled roof, pierced by a single chimney; one window is set into the side, and the front has space for just one window and the main entrance. Its location on a slope permits the slight exposure of the foundation on one side. Smaller elements include shutters for the windows and a pair of steps that provide access to the main entrance.{{OHC NRHP|70000523|Ohio Company Land Office}}, Ohio History Connection, 2015. Accessed 2016-01-03. As the oldest extant building anywhere in Ohio, the land office had become the focus of significant attention by the opening years of the twentieth century, with organizations such as Marietta's historical society devoting extensive effort to ensure its preservation.

The building is now part of the Campus Martius Museum complex.