Item 2. PROPERTIES

We conduct our research, development, manufacturing, and administrative activities at our owned and leased facilities. A summary of our significant owned and leased properties is provided below.

Tarrytown, New York

At our Tarrytown, New York location, we lease approximately 1,467,000 square feet of laboratory and office space, of which approximately 1,180,000 square feet is occupied by Regeneron. Refer to Part II, Item 7. "Management's Discussion and Analysis of Financial Condition and Results of Operations - Liquidity and Capital Resources - Tarrytown, New York Leases" for further details. We also own an approximate 100-acre parcel of undeveloped land adjacent to our Tarrytown, New York location; we intend to develop this property to accommodate and support our growth, primarily in connection with expanding our existing research and development and office space.

Sleepy Hollow, New York

We own an office building in Sleepy Hollow, New York, consisting of approximately 383,000 square feet. This facility is being used as additional office space to support the growth of our existing Tarrytown facilities.

Rensselaer, New York

We own facilities in Rensselaer, New York totaling approximately 565,000 square feet of research, manufacturing, office, and warehouse space. In 2018, we also purchased approximately 124,000 square feet of research and office space near our Rensselaer facility, a portion of which we had previously leased. We also own approximately 130 acres of land near our Rensselaer facility; we developed approximately 212,000 square feet on this property in connection with expanding our warehouse space, and we have plans to further develop this property in connection with expanding certain manufacturing activities.

Troy, New York

We own an office building in Troy, New York, consisting of approximately 217,000 square feet, which we are utilizing as additional office space to support the growth of our existing Rensselaer facilities.

Limerick, Ireland

We own a manufacturing facility in Limerick, Ireland, consisting of approximately 445,000 square feet, which was purchased and subsequently renovated to accommodate and support our growth and expand our manufacturing capacity. The facility has received certain manufacturing approvals by regulatory agencies, including the FDA.