without a design degree?
First, congrats on your interest in architecture. As you are in the midst of completing your undergraduate degree in marketing, you are certainly eligible to apply to any number of Master of Architecture degree programs across the country. In most cases, you will take between 3-4 years to complete the degree. To start the research process, consider visiting the following:
ARCHSchools.org - http://www.archschools.org
NAAB - http://www.naab.org
Both will provide you a list of the programs with more detailed information along with contact information. In the DC region, you may consider UMaryland, CatholicU among others. Unfortunately, Howard does NOT have the graduate degree, but you should consider taking a course from the School of Architecture at Howard next spring to generate material for your portfolio. All graduate programs require a portfolio regardless of your background.
To gain experience, touch base with your internship supervisor for ideas. Visit the National Building Museum and others to gain exposure. I did find this group.