This image is a view of the American Falls as seen from Queen Victoria Park on the Canadian side of the river.

There is no description on the back of the card, only the legend printed above the falls on the front.
The boat depicted is the famous Maid of the Mist tour boat, which was first used in ferry service before the American Civil War. It was relaunched as a tour boat service in 1895.
The image was originally black and white, then professionally colored. However, the pink ring on the image is a stain from a glass. The postcard was used and is dated 1957.
Tag: postcard
Falls Viewed from Rainbow Bridge, Niagara Falls, Canada
This image is taken from a similar, but from the Rainbow Bridge, further downstream from the viewing area in the previous photo. It is composed to make the falls look more wild and natural, as the only obvious modern presence is the tour boat in the left center of the photo. This boat is the famous Maid of the Mist.

The description states:
NIAGARA FALLS FROM RAINBOW BRIDGE
Niagara Falls, Ontario, Canada
A breathtaking sight of Mother Nature’s great masterpiece. Niagara Falls, as seen from man’s great accomplishment, Rainbow Bridge, a beautiful combination of Power and Art.
–The bridge was built beginning in 1939 and completed in 1941 as a replacement for the older Honeymoon Bridge which collapsed from an ice jam on the river.
This card was used and is dated 1956.
American and Horseshoe Falls, Niagara Falls, Canada
This image shows both of the large cascades that make up the Niagara Falls complex, as seen from the Canadian side of the border.

The description states:
THE AMERICAN AND HORSESHOE FALLS
Niagara Falls, Canada
Seen from the Canadian side of Niagara
–The postcard was used and is dated 1952, which is consistent with the models of cars seen parked in the photo. The link above has another photo of this same area as it now exists, and the viewing area is still present, but much more fully developed.
Maple Leaf Cabins, Niagara Falls, Canada
This image begins a series of cards featuring the world famous Niagara Falls, long a site for honeymooners and other vacationeers.

This is one of the old style cards that did not have any description listed on the back, just printed guide marks for postage, address and message. The signs visible on the front of the main office indicate that this was also something of a general store.
The address no longer exists, since the numbers for the street were changed sometime in the past, but the current business at this same location is still a tourist hotel.
The vehicles visible in the photo indicate that this image is from the 1940s.
Brooke Army Hospital, Fort Sam Houston, Texas
This image is of the main hospital building for the Brooke Army Medical Center as it existed in the 1960s. In addition to this, there were other buildings added for treatment and patient housing when this building became too small or had inadequate facilities for modern treatment.

The description states:
BROOKE ARMY HOSPITAL
Brooke Army Medical Center
Fort Sam Houston
San Antonio, Texas
–This older building was replaced in 1997 with a larger, more modern facility on the grounds of Fort Sam Houston where more treatment modalities could be concentrated in a single structure. The older building is now on the Register of Historic Places and is occupied by elements of U.S. Army South.
This image dates from the 1960s.
Alamo Plaza, San Antonio, Texas
This is an elevated view of Alamo Plaza in the middle of San Antonio’s downtown. The mission chapel can be seen at the far right foreground with the white roof. This illustrates the urban development that has risen around the mission.

The description states:
ALAMO PLAZA
San Antonio, Texas
–The monument in the center of the plaza is a cenotaph, and honors those that died in the siege. The flowers around the monument were replaced in later years with trees, and the monument is somewhat obscured by them now, rather than being visible from all directions.
The building in the right background is the Federal Courthouse, and the building at the extreme right is the Emily Morgan Hotel, named for Emily West, a mixed race woman who lived during the time of the Alamo siege.
This image dates from the 1960s.
Interior of Alamo Chapel, San Antonio, Texas
This image shows the chapel interior, where originally services would be held when the mission was active. Now it is used to display historical artifacts and illustrations for visitors to the park.

The description states:
THE INTERIOR OF THE ALAMO
SAN ANTONIO, TEXAS
–Note the signs posted along the side of the reception desk at right. One unusual one states “Gentlemen will remove hats Please”. This is likely posted because this was once a sanctuary.
The card dates from the 1960s.
Alamo Mission Chapel and Park, San Antonio, Texas
This image shows the front of the mission chapel from a slightly different angle, with the paths and grass of the park more clearly shown. The flag flying on the left of the building is the state flag of Texas, called the Lone Star flag.

The description states:
THE ALAMO
SAN ANTONIO, TEXAS
“Cradle of Texas Liberty”
–The flag shown was not present during the siege, and another, the Alamo flag, was also not likely present at the battle. There are no definitive records of the flag used.
This card dates from the 1960s.
Alamo Mission, Side View with Gate, San Antonio, Texas
This image, with the benefit of the warming colors of the sun, shows the main entrance to the mission chapel through the gate to the park.

The description states:
THE ALAMO, SAN ANTONIO TEXAS
Built in 1718, this edifice is one of the most important points of interest in the history-steeped city of San Antonio.
–The postcard dates from the 1960s.
Alamo Mission Full View, San Antonio, Texas
This image, following on the previous, shows a more comprehensive view of the park where the historical mission is located. The century plant in the left foreground is the same as in the previous picture.

The description states:
THE ALAMO, SAN ANTONIO TEXAS
“Cradle of Texas Liberty,” founded in 1718 as the Mission San Antonio de Valero.
–As noted in the linked article, the preservation and restoration of the Alamo was difficult and often contentious, with the state of Texas stepping in at various times to mediate between opposing parties.
The postcard dates from the 1960s.