Designed by the architects Carrère and Hastings, the Alcazar was the second resort hotel built by Henry Flagler in St. Augustine. The building was initially conceived as a recreational entertainment annex for the grander Hotel Ponce de Leon, but the design was soon revised and expanded to create an independent hotel. The Alcazar opened on Christmas Day, 1888.

The Hotel Alcazar is a monolithic structure of poured concrete. Flagler’s St. Augustine hotels were the first large multistory concrete buildings in the United States. The concrete façade is enlivened with intricate terracotta detailing, and crowned with roofs of red tile. The mass of the façade is punctuated at regular intervals by large arched windows at street level and smaller rectangular windows above. Twin towers draw the eye skyward, up and away from the grey mass of concrete. The towers are crowned with elaborate belvederes of terra-cotta and red brick. 

The plan of the Alcazar comprised three distinct units, the hotel, the baths, and the casino. At the north end of the complex, the hotel rooms framed an interior courtyard, lush with tropical plants and lined with a covered arcade of luxury goods stores. What distinguished the Alcazar from the grander Ponce de Leon Hotel was its indoor entertainment and recreational facilities, which proved popular with guests and locals alike. The central area of the hotel was dedicated to the baths, a series of spaces designed for the health and wellbeing of hotel guests. To the south was the Casino, a vast four-story space featuring a substantial indoor swimming pool, a grand ballroom, and a bowling alley. Beyond the Casino a croquet lawn and tennis courts completed the hotel’s entertainments.

As the twentieth century wore on, changing tastes and increased options for vacationing meant that Flagler’s St. Augustine hotels witnessed an ongoing decline in visitation. Following the Wall Street Crash of 1929, and the ensuing Depression, the Alcazar closed its doors as a hotel in 1931.